Magnetic phase-transformation material

Abstract

A magnetic phase-transformation material with the formula Ni.sub.amMn.sub.bnCo.sub.m+nTi.sub.c is provided, wherein a+b+c=100, 20<a90, 5b<50, 5c30, 0ma, 0nb, 0<m+n<a+b, and wherein, any one or combination of a, b, c, m, n represent an atomic percentage content. The magnetic phase-transformation material has properties of high toughness, high deformation rate, ferromagnetism and magnetic field-driven martensitic phase transformation, which can be widely used in various fields including high-strength and high-toughness actuators, temperature and/or magnetic sensitive elements, magnetic refrigeration devices and equipments, magnetic heat pump devices, magnetic memories, micro-electromechanical devices and systems, and thermomagnetic power generators or transducers.

Claims

1. A magnetic phase-transformation material with the formula: Ni.sub.amMn.sub.bnCo.sub.m+nTi.sub.c, wherein a+b+c=100, 20<a90, 5b<50, 5c30, 0ma, 0nb, 0<m+n<a+b, and wherein, any one or combination of a, b, c, m, n represent an atomic percentage content.

2. The magnetic phase-transformation material of claim 1, wherein 28am57.

3. The magnetic phase-transformation material of claim 1, wherein 13bn37.

4. The magnetic phase-transformation material of claim 1, wherein 5m+n16.

5. The magnetic phase-transformation material of claim 1, wherein 8c26.

6. The magnetic phase-transformation material of claim 1, wherein the formula is Ni.sub.40Mn.sub.30Co.sub.14Ti.sub.16.

7. The magnetic phase-transformation material of claim 1, wherein the formula is Ni.sub.36.5Mn.sub.35Co.sub.13.5Ti.sub.15.

8. The magnetic phase-transformation material of claim 1, wherein the formula is Ni.sub.35Mn.sub.35Co.sub.15Ti.sub.15.

9. The magnetic phase-transformation material of claim 1, wherein the formula is Ni.sub.57Mn.sub.14Co.sub.16Ti.sub.13.

10. The magnetic phase-transformation material of claim 1, wherein the formula is Ni.sub.28Mn.sub.37Co.sub.12Ti.sub.23.

11. A method of preparing a magnetic phase-transformation material with the formula: Ni.sub.amMn.sub.bnCo.sub.m+nTi.sub.c, wherein a+b+c=100, 20<a90, 5b<50, 5c30, 0ma, 0nb, 0<m+n<a+b, and wherein, any one or combination of a, b, c, m, n represent an atomic percentage content comprising: weighing materials of Ni, Co, Mn, Ti in accordance with the formula; and preparing the magnetic phase-transformation material from the weighed materials by a Czochralski method or zone melting method or directional solidification method.

12. The method of claim 11, wherein 28am57.

13. The method of claim 11, wherein 13bn37.

14. The method of claim 11, wherein 5m+n16.

15. The method of claim 11, wherein 8c26.

16. The method of claim 11, wherein the magnetic phase-transformation material is prepared by a Czochralski method.

17. The method of claim 11, wherein the magnetic phase-transformation material is prepared by a zone melting method.

18. The method of claim 11, wherein the magnetic phase-transformation material is prepared by a directional solidification method.

19. The method of claim 11, wherein the formula is Ni.sub.40Mn.sub.30Co.sub.14Ti.sub.16, Ni.sub.36.5Mn.sub.35Co.sub.13.5Ti.sub.15, Ni.sub.35Mn.sub.35Co.sub.15Ti.sub.15.9, Ni.sub.57Mn.sub.14Co.sub.16Ti.sub.13, or Ni.sub.28Mn.sub.37Co.sub.12Ti.sub.23.

Description

BRIEF DESCRIPTION OF ACCOMPANYING DRAWINGS

(1) Embodiments of the present invention will be explained in detail with reference to the accompanying drawings, wherein:

(2) FIG. 1 shows the isothermal magnetization curve of a material of Ni.sub.40Mn.sub.30Co.sub.14Ti.sub.16 according to the first embodiment of the present invention;

(3) FIG. 2 shows the resistance-magnetic field curve of the material of Ni.sub.40Mn.sub.30Co.sub.14Ti.sub.16 according to the first embodiment of the present invention, as driven by a magnetic field;

(4) FIG. 3 shows the stress-strain curve of a material of Ni.sub.36.5Mn.sub.35Co.sub.13.5Ti.sub.15 according to the sixth embodiment of the present invention, and that of a material of Ni.sub.2MnGa according to Comparative Example 1;

(5) FIG. 4 shows the magnetization-temperature relation curve of the material of Ni.sub.36.5Mn.sub.35Co.sub.13.5 Ti.sub.15 according to the sixth embodiment of the present invention;

(6) FIG. 5 shows the magnetocaloric effect characteristic curve of a material of Ni.sub.35Mn.sub.35Co.sub.15 Ti.sub.15 according to the seventh embodiment of the present invention;

(7) FIG. 6 shows the megnetostrain characteristic curve of a material of Ni.sub.57Mn.sub.14Co.sub.16Ti.sub.13 according to the eighth embodiment of the present invention; and

(8) FIG. 7 shows the powder XRD spectrum of a material of Ni.sub.28Mn.sub.37Co.sub.12Ti.sub.23 in the parent phase according to the tenth embodiment of the present invention.

DESCRIPTION OF EMBODIMENTS

(9) In the following parts, the present invention will be described in greater details with reference to the embodiments and the accompanying drawings. It should be understood that the specific embodiments described herein only intend to interpret the present invention, without making any limitation thereto.

(10) In the following various embodiments, the present inventors have measured the isothermal magnetization curves, resistance-magnetic field curves, stress-strain curves, magnetization-temperature relation curves, magnetocaloric effect characteristic curves, megnetostrain curves, and powder XRD spectrums of the samples obtained, for illustrating the relevant properties of the materials of the present invention. For simplicity, however, results of only several of the samples are shown, and the other samples have similar results for corresponding properties.

The First Embodiment

(11) A magnetic phase-transformation material of Ni.sub.40Mn.sub.30Co.sub.14Ti.sub.16 with high toughness is prepared in this embodiment, and the preparation method comprises:

(12) Step 1: weighing 100 g in total for materials of Ni, Co, Mn, Ti with purity of 99.9% in accordance with the formula Ni.sub.40Mn.sub.30Co.sub.14Ti.sub.16;

(13) Step 2: inputting the weighed materials into a magnetic levitation cold crucible, raising the temperature to 1280 C. for melting them with a radio frequency of 245 kHz and a power of 20 kW under the condition of Ar of 0.1Mpa as the shielding gas, and maintaining at 1280 C. for 30 min; and then cooling down to the room temperature to form a smelted ingot as a raw material for later use;

(14) Step 3: growing single crystals of Ni.sub.40Mn.sub.30Co.sub.14Ti.sub.16 with the conventional Czochralski method, in which the ingot obtained in Step 2 is heated in the above magnetic levitation cold crucible to 1280 C. and maintained for 30 min, and small single crystals of Ni.sub.40Mn.sub.30Co.sub.14Ti.sub.16 with a size of 2 mm2 mm7 mm are cut from the smelted ingot obtained in Step 2 as seed crystals, the bottoms of the seed crystals are brought in contact with the liquid level of the melted raw material at a rotation speed of 30 rounds/min and then, the seed crystal rod is lifted at a uniform speed of 30 mm/h so as to lift up the solidified crystal, during which the temperature of the melted raw material is adjusted for enabling the diameter of the growing crystal to increase from 2 mm to 10 mm and then remained unchanged until a high-quality single crystals of Ni.sub.40Mn.sub.30Co.sub.14Ti.sub.16 with a diameter of 10 mm and a length of 100 mm is obtained;

(15) Step 4: lifting the single crystal rods of Ni.sub.40Mn.sub.30Co.sub.14Ti.sub.16 obtained in Step 3 out of the surface of the melted raw material, cooling down slowly to the room temperature at a cooling rate of 10 C./min, and finally taking out of the crucible;

(16) Step 5: heat-treating the sample obtained in Step 4 for 72 hours at 1000 C., cooling down to 500 C., and then heat-treating again for 48 hours, and subsequently cooling down at a cooling rate of 10 C./s to make the obtained sample of Ni.sub.40Mn.sub.30Co.sub.14Ti.sub.16 have higher component homogeneity and atomic ordering.

(17) The aforementioned various properties of the obtained single crystals of Ni.sub.40Mn.sub.30Co.sub.14Ti.sub.16 are measured, the characteristic curves thereof are collected, and the corresponding parameters are computed.

(18) The isothermal magnetization curve of Ni.sub.40Mn.sub.30Co.sub.14Ti.sub.16, as shown in FIG. 1, is obtained by using the Physical Property Measurement System (PPMS, Quantum Design Inc., US) at the temperature of 280K and under the normal pressure, which indicates the magnetism and the property of magnetic field-driven martensitic phase transformation of this material, and it can be seen that this material can be driven from the martensitic phase to the parent phase by applying a magnetic field. The resistance-magnetic field curve of Ni.sub.40Mn.sub.30Co.sub.14Ti.sub.16 driven by magnetic field, as shown in FIG. 2, is also obtained by using the Physical Property Measurement System at the temperature of 280K and under the normal pressure, which indicates the magnetoresistance property of this material, and it can be seen that the resistance of this material may have a change of 45% under the magnetic field. Table 1 shows the corresponding values of compressive strength, deformation rate, toughness, magnetic field driving efficiency (dT/dH), magnetostrain (), magnetoresistance (MR) and magnetic entropy change (S) of the material of Ni.sub.40Mn.sub.30Co.sub.14Ti.sub.16.

The Second Embodiment

(19) A magnetic phase-transformation material of Ni.sub.44Mn.sub.33Co.sub.15Ti.sub.8 with high toughness is prepared in this embodiment, and the preparation method comprises:

(20) Step 1: weighing 200 g in total for materials of Ni, Co, Mn, Ti with purity of 99.9% in accordance with the formula Ni.sub.44Mn.sub.33Co.sub.15Ti.sub.8;

(21) Step 2: inputting the weighed materials into a quartz crucible, raising the temperature to 1300 C. with a radio frequency of 245 kHz and a power of 20 kW under the condition of Ar of 0.01Mpa as the shielding gas, and maintaining at 1300 C. for 20 min; and then cooling down to the room temperature to form a smelted ingot as the raw material for later use.

(22) Step 3: growing magnetic crystal of Ni.sub.44Mn.sub.33Co.sub.15Ti.sub.8 with the conventional zone melting method, in which the ingot obtained in Step 2 is heated in the above quartz crucible to 1300 C. and maintained for 20 min, and single crystals of Ni.sub.44Mn.sub.33Co.sub.15Ti.sub.8 with [111] orientation and with a size of 2 mm2 mm7 mm are cut from the smelted ingot obtained in Step 2 as seed crystals, and then the seed crystals are arranged at one end of a quartz boat, and the melted raw material and the heating zone are made to move with respect to each other at a speed of 10 mm/h to form a solidified single crystals, obtaining a single crystal of Ni.sub.44Mn.sub.33Co.sub.15Ti.sub.8 with a width of 20 mm and a length of 50 mm;

(23) Step 4: cooling down the single crystals of Ni.sub.44Mn.sub.33Co.sub.15Ti.sub.8 obtained in Step 3 slowly to the room temperature at a cooling rate of 10 C./min;

(24) Step 5: annealing the sample obtained in Step 4 for 20 hours at 1000 C., and then cooling at a cooling rate of 100 C./s to make the obtained material of Ni.sub.44Mn.sub.33Co.sub.15Ti.sub.8 have higher component homogeneity and atomic ordering.

(25) The aforementioned various properties of the obtained single crystals of Ni.sub.44Mn.sub.33Co.sub.15Ti.sub.8 are measured and the characteristic curves thereof are collected, and the corresponding parameters are computed. Table 1 shows the values of compressive strength, deformation rate, toughness, magnetic field driving efficiency (dT/dH), magnetostrain (), magnetoresistance (MR) and magnetic entropy change (S) of the material of Ni.sub.44Mn.sub.33Co.sub.15Ti.sub.8.

The Third Embodiment

(26) A magnetic phase-transformation material of Ni.sub.51Mn.sub.13Co.sub.10Ti.sub.26 with high toughness is prepared in this embodiment, and the preparation method comprises:

(27) Step 1: weighing 260 g in total for materials of Ni, Co, Mn, Ti with purity of 99.9% in accordance with the formula Ni.sub.51Mn.sub.13Co.sub.10Ti.sub.26;

(28) Step 2: inputting the weighed materials into a quartz crucible with a diameter of 20 mm, raising the temperature to 1330 C. for melting them with a radio frequency of 245 kHz and a power of 25 kW under the condition of N.sub.2 as the shielding gas with a positive pressure of 0.2 MPa, and maintaining at 1330 C. for 10 min.

(29) Step 3: obtaining a polycrystalline orientation material of Ni.sub.51Mn.sub.13Co.sub.10Ti.sub.26 with a diameter of 20 mm and a length of 100 mm at a growing speed of 30 mm/h by the conventional directional solidification method;

(30) Step 4: cooling down the polycrystalline of Ni.sub.51Mn.sub.13Co.sub.10Ti.sub.26 obtained in Step 3 slowly to the room temperature at a cooling rate of 10 C./min;

(31) Step 5: annealing the sample obtained in Step 4 for 5 hours at 1200 C., and then cooling at a cooling rate of 20 C./min to make the obtained material of Ni.sub.51Mn.sub.13Co.sub.10Ti.sub.26 have higher component homogeneity and atomic ordering.

(32) The aforementioned various properties of the obtained material of Ni.sub.51Mn.sub.13Co.sub.10Ti.sub.26 are measured and the characteristic curves thereof are collected, and the corresponding parameters are computed. Table 1 shows the values of compressive strength, deformation rate, toughness, magnetic field driving efficiency (dT/dH), magnetostrain (), magnetoresistance (MR) and magnetic entropy change (S) of the material of Ni.sub.51Mn.sub.13Co.sub.10Ti.sub.26.

The Fourth Embodiment

(33) A magnetic phase-transformation material of Ni.sub.45Mn.sub.31Co.sub.5Ti.sub.19 with high toughness is prepared in this embodiment by the directional solidification method adopted in the third embodiment, and the differences of both embodiments lie in that: the raw materials weigh 1200 g in total in accordance with the formula; the quartz crucible has a diameter of 30 mm, and N.sub.2 is used as the shielding gas under a positive pressure of 0.8 Mpa; the raw materials are heated to 1380 C. at a power of 40 kW and maintained at 1380 C. for 30 min; the growing speed is 10 mm/h, and the obtained material is annealed for 100 hours at 800 C., and then cooled at a cooling rate of 10000 C./s; and thus, a polycrystalline orientation material of Ni.sub.45Mn.sub.31Co.sub.5Ti.sub.19 with a diameter of 30 mm and a length of 200 mm is obtained;

(34) The aforementioned various properties of the obtained material of Ni.sub.45Mn.sub.31Co.sub.5Ti.sub.19 are measured and the characteristic curves thereof are collected, and the corresponding parameters are computed. Table 1 shows the values of compressive strength, deformation rate, toughness, magnetic field driving efficiency (dT/dH), magnetostrain (), magnetoresistance (MR) and magnetic entropy change (S) of the material of Ni.sub.45Mn.sub.31Co.sub.5Ti.sub.19.

The Fifth Embodiment

(35) A magnetic phase-transformation material of Ni.sub.49.5Mn.sub.24Co.sub.15.5Ti.sub.11 with high toughness is prepared in this embodiment by the same method as that of the third embodiment except that the growing speed is 5 mm/h.

(36) The obtained material of Ni.sub.49.5Mn.sub.24Co.sub.15.5Ti.sub.11 is heated to 500 C. and rolled down into a profile with a width of 50 mm and a height of 5 mm, and the length of the profile is not limited. The aforementioned various properties are measured and the characteristic curves thereof are collected for the profile, and the corresponding parameters are computed. Table 1 shows the values of compressive strength, deformation rate, toughness, magnetic field driving efficiency (dT/dH), magnetostrain (), magnetoresistance (MR) and magnetic entropy change (S) of the profile of Ni.sub.49.5Mn.sub.24Co.sub.15.5 Ti.sub.11.

The Sixth Embodiment

(37) A magnetic phase-transformation material of Ni.sub.36.5Mn.sub.35Co.sub.13.5Ti.sub.15 with high toughness is prepared in this embodiment by the same method as that of the fourth embodiment except that the growing speed is 15 mm/h.

(38) The obtained material of Ni.sub.36.5Mn.sub.35Co.sub.13.5Ti.sub.15 is rolled down into a sheet of profile with a length of 2000 mm, a width of 300 mm and a thickness of 1 mm. The aforementioned various properties are measured and the characteristic curves thereof are collected for the profile, and the corresponding parameters are computed. The stress-strain curve of the material of Ni.sub.36.5Mn.sub.35Co.sub.13.5Ti.sub.15, as shown in FIG. 3, is obtained by the common stress-strain measuring equipment at the room temperature, which indicates the toughness and deformation rate of the material with the shadow area representing the value of toughness. The magnetism-temperature relation curve of the material of Ni.sub.36.5Mn.sub.35Co.sub.13.5Ti.sub.15, as shown in FIG. 4, is obtained by the SQUID magnetometer of Quantum Design. Inc., US, which indicates the property of martensitic phase-transformation of the material. Table 1 shows the values of compressive strength, deformation rate, toughness, magnetic field driving efficiency (dT/dH), magnetostrain (), magnetoresistance (MR) and magnetic entropy change (S) of the profile of Ni.sub.36.5Mn.sub.35Co.sub.13.5Ti.sub.15.

The Seventh Embodiment

(39) A magnetic phase-transformation material of Ni.sub.35Mn.sub.35Co.sub.15Ti.sub.15 with high toughness is prepared in this embodiment by the same method as that of the fourth embodiment except that the growing speed is 20 mm/h.

(40) The obtained material of Ni.sub.35Mn.sub.35Co.sub.15Ti.sub.15 is rolled down into a sheet of profile with a length of 1000 mm, a width of 150 mm and a thickness of 3 mm at the temperature of 650 C. The aforementioned various properties are measured and the characteristic curves thereof are collected for this profile, and the corresponding parameters are computed. The magnetocaloric effect characteristic curve of the material of Ni.sub.35Mn.sub.35Co.sub.15Ti.sub.15, as shown in FIG. 5, is obtained by the Physical Property Measurement System (PPMS, Quantum Design. Inc., US), which indicates the magnetocaloric effect of such material. Table 1 shows the values of compressive strength, deformation rate, toughness, magnetic field driving efficiency (dT/dH), magnetostrain (), magnetoresistance (MR) and magnetic entropy change (S) of the material of Ni.sub.35Mn.sub.35Co.sub.15Ti.sub.15.

The Eighth Embodiment

(41) A magnetic phase-transformation material of Ni.sub.57Mn.sub.14Co.sub.16Ti.sub.13 with high toughness is prepared in this embodiment by the same method as that of the first embodiment except that: the materials weigh 200 g in total in accordance with the formula; the crucible is quartz crucible; the seed crystal rotation speed is 20 rounds/min; and the growing speed is 30 mm/h.

(42) The aforementioned various properties of the obtained material of Ni.sub.57Mn.sub.14Co.sub.16Ti.sub.13 are measured and the characteristic curves thereof are collected, and the corresponding parameters are computed. The megnetostrain characteristic curve of the material of Ni.sub.57Mn.sub.14Co.sub.16Ti.sub.13, as shown in FIG. 6, is obtained by using the Physical Property Measurement System (PPMS, Quantum Design. Inc., US), which indicates the strain property of such material under the magnetic field. Table 1 shows the corresponding values of compressive strength, deformation rate, toughness, magnetic field driving efficiency (dT/dH), magnetostrain (), magnetoresistance (MR) and magnetic entropy change (S) of the material of Ni.sub.57Mn.sub.14Co.sub.16Ti.sub.13.

The Ninth Embodiment

(43) A magnetic phase-transformation material of Ni.sub.35Mn.sub.36.5Co.sub.10.5Ti.sub.18 with high toughness is prepared in this embodiment by the same method as that of the third embodiment except that heat treatment of Step 5 is omitted.

(44) The aforementioned various properties of the obtained material of Ni.sub.35Mn.sub.36.5Co.sub.10.5Ti.sub.18 are measured and the characteristic curves thereof are collected, and the corresponding parameters are computed. Table 1 shows the values of compressive strength, deformation rate, toughness, magnetic field driving efficiency (dT/dH), magnetostrain (), magnetoresistance (MR) and magnetic entropy change (S) of the material of Ni.sub.35Mn.sub.36.5Co.sub.10.5Ti.sub.18.

The Tenth Embodiment

(45) A magnetic phase-transformation material of Ni.sub.28Mn.sub.37Co.sub.12Ti.sub.23 with high toughness is prepared in this embodiment, and the preparation method is as follows:

(46) Step 1: weighing 1000 g in total for materials of Ni, Co, Mn, Ti with purity of 99% in accordance with the formula Ni.sub.28Mn.sub.37Co.sub.12Ti.sub.23;

(47) Step 2: inputting the weighed materials into a graphite crucible, raising the temperature to 1350 C. in a vacuum of 510.sup.3 Pa for melting, and maintaining for 20 min;

(48) Step 3: effusing the melted materials obtained in Step 2 from the edge of the graphite crucible to the outer surface of a copper wheel which rotate at a linear speed of 50 m/s, and then solidifying quickly to form a sheet with a thickness of 3 mm;

(49) Step 4: annealing the prepared sheet for 100 hours at 800 C., then cooling at a cooling rate of 5000 C./s to make the obtained material of Ni.sub.28Mn.sub.37Co.sub.12Ti.sub.23 have higher component homogeneity and atomic ordering.

(50) The aforementioned various properties of the obtained material of Ni.sub.28Mn.sub.37Co.sub.12Ti.sub.23 are measured and the characteristic curves thereof are collected, and the corresponding parameters are computed. The powder XRD spectrum of the material of Ni.sub.28Mn.sub.37Co.sub.12Ti.sub.23 in the parent phase, as shown in FIG. 7, is obtained by the conventional X-ray diffractometer at the normal temperature and under the normal pressure, which indicates the basic crystal structure of such material is body-centered cubic structure. Table 1 shows the values of compressive strength, deformation rate, toughness, magnetic field driving efficiency (dT/dH), magnetostrain (), magnetoresistance (MR) and magnetic entropy change (S) of the material of Ni.sub.28Mn.sub.37Co.sub.12Ti.sub.23.

The Eleventh Embodiment

(51) A magnetic phase-transformation material of Ni.sub.53Mn.sub.16Co.sub.14Ti.sub.17 with high toughness is prepared in this embodiment, and the preparation method comprises:

(52) Step 1: weighing 500 g in total for materials of Ni, Co, Mn, Ti with purity of 95% in accordance with the formula;

(53) Step 2: inputting the weighed materials into the quartz crucible, and raising the temperature to 1350 C. in the atmosphere and under the normal pressure for melting and maintaining for 20 min;

(54) Step 3: effusing the melted materials into a foundry casting mould and solidifying to a raw material ingot;

(55) Step 4: rolling the raw material ingot down into a profile with a width of 5 mm and a height of 5 mm, wherein the length of the profile is not limited.

(56) The aforementioned various properties of the obtained material of Ni.sub.53Mn.sub.16Co.sub.14Ti.sub.17 are measured and the characteristic curves thereof are collected, and the corresponding parameters are computed. Table 1 shows the corresponding values of compressive strength, deformation rate, toughness, magnetic field driving efficiency (dT/dH), magnetostrain (), magnetoresistance (MR) and magnetic entropy change (S) of the material of Ni.sub.53Mn.sub.16Co.sub.14Ti.sub.17.

Comparative Example

(57) Various properties of a Heusler magnetic phase-transformation material of Ni.sub.2MnGa are shown as the Comparative Example in Table 1. Ni.sub.2MnGa alloy is an important and well known magnetic phase-transformation material at present, which is prepared with the similar method to that of the first embodiment according to the formula of Ni.sub.2MnGa, and its stress-strain curve (see FIG. 3) is measured to show compressive strength, deformation rate and toughness of the material of Ni.sub.2MnGa, the three of which are important parameters representing strength and toughness. As can be seen from FIG. 3, the compressive strength of the present invention sample Ni.sub.36.5Mn.sub.35Co.sub.13.5Ti.sub.15 is 1150 MPa, while the compressive strength of the Ni.sub.2MnGa is 300 MPa and the deformation rate and the toughness thereof both are zero. Other property parameters of Ni.sub.2MnGa, such as isothermal magnetization curve, resistance-magnetic field curve, magnetization-temperature relation curve, magnetocaloric effect curve and megnetostrain characteristic curve, are found from the currently available published literatures, for example, Large magnetic entropy change in a Heusler alloy Ni.sub.52.6Mn.sub.23.1Ga.sub.24.3 single crystal, Feng-xia Hu, Bao-gen Shen, Ji-rong Sun, and Guang-heng Wu et al., published in Phys. Rev. B., Vol. 64, Page 132412, and the best parameters are selected therefrom and shown in table 1 in order to compare with those of the present invention materials. It can be seen from table 1 that the compressive strength, the deformation rate and the toughness of the present materials are much higher than those of the material of Ni.sub.2MnGa.

(58) According to other embodiments of the present invention, the purities of Ni, Co, Mn, Ti composing the magnetic phase-transformation materials of Ni.sub.amMn.sub.bnCo.sub.m+nTi.sub.c are between 9099.9999%.

(59) According to other embodiments of the present invention, the magnetic phase-transformation materials of Ni.sub.amMn.sub.bnCo.sub.m+nTi.sub.c may be heated to be melted through arc heating, conventional Muffle furnace heating or the other heating methods well known in the art.

(60) According to still further embodiments of the present invention, the crucible for holding the raw materials of the magnetic phase-transformation materials of Ni.sub.amMn.sub.bnCo.sub.m+nTi.sub.c may be water-cooled copper crucible or other crucibles well known in the art.

(61) According to other embodiments of the present invention, the temperature for heating the raw materials of the magnetic phase-transformation materials of Ni.sub.amMn.sub.bnCo.sub.m+nTi.sub.c and melting them may be between 1280 C.1400 C., the atmosphere for melting may be a vacuum of 110.sup.2510.sup.5 Pa, or a shielding gas of 0.010.2 MPa such as Ar, N.sub.2, or common atmosphere, and the duration maintained in the melted state may be 0.160 minutes.

(62) According to still another embodiment of the present invention, the magnetic phase-transformation materials of Ni.sub.amMn.sub.bnCo.sub.m+nTi.sub.c prepared with the Czochralski method, may grow at a growing speed of 380 mm/h; the seed crystal rod rotates at a rotation speed of 0.550 rounds/min; the used seed crystal may be single crystals or polycrystalline having same or similar components and required orientation; and the obtained bulk of materials of Ni.sub.amMn.sub.bnCo.sub.m+nTi.sub.c may be single crystals or polycrystalline rods.

(63) According to still further another embodiment of the present invention, the magnetic phase-transformation materials of Ni.sub.amMn.sub.bnCo.sub.m+nTi.sub.c prepared with the conventional zone melting method, may grow at a growing speed of 380 mm/h; the used seed crystal may be single crystals or polycrystalline having same or similar components and required orientation; or need no seed crystal. The obtained bulk of materials of Ni.sub.amMn.sub.bnCo.sub.m+nTi.sub.c may be single crystals or polycrystalline rods.

(64) According to still further another embodiment of the present invention, the method of solidifying various melted magnetic materials of Ni.sub.amMn.sub.bnCo.sub.m+nTi.sub.c may be performed as follows: cooling at a determined cooling rate, or pouring into a mould, or pouring onto the surface of a metal having good thermal conductivity, or pouring into various liquids. The above methods can realize slow cooling or rapid cooling, thereby obtaining various shapes of the materials of Ni.sub.amMn.sub.bnCo.sub.m+nTi.sub.c, including bulk, thin strip, sheet or filament, and so on.

(65) According to another embodiment of the present invention, the temperature for the heating treatment to the materials of Ni.sub.amMn.sub.bnCo.sub.m+nTi.sub.c may be at 200 C.1200 C. and the time may be 0.011000 hours, so that the obtained materials of Ni.sub.amMn.sub.bnCo.sub.m+nTi.sub.c can have higher component homogeneity and atomic ordering.

(66) According to still another embodiment of the present invention, the obtained materials of Ni.sub.amMn.sub.bnCo.sub.m+nTi.sub.c may be rolled down at a rolling temperature between 130 C.900 C. While the present invention has been described with reference to the preferred embodiments, it is recognized that the present invention is not limited to the embodiments described above, but includes various changes and modifications made without departing from the scope of the present invention.

(67) TABLE-US-00001 TABLE 1 Compressive Deformation Toughness dT/dH MR S Compositions strength (MPa) rate (%) (MPa .Math. %) (K/T) (%) (%) (J/kgK) The first 1100 18 12050 8.2 4.1 45 12 embodiment Ni.sub.40Mn.sub.30Co.sub.14Ti.sub.16 The second 960 26 13610 3.7 6.0 57 22 embodiment Ni.sub.44Mn.sub.33Co.sub.15Ti.sub.8 The third 1300 15 14650 3.8 6.2 46 21 embodiment Ni.sub.51Mn.sub.13Co.sub.10Ti.sub.26 The fourth 840 12 10560 4 5.5 32 17 embodiment Ni.sub.45Mn.sub.31Co.sub.5Ti.sub.19 The Fifth 1300 30 27630 8.4 4 35 11 embodiment Ni.sub.49.5Mn.sub.24Co.sub.15.5Ti.sub.11 The sixth 1150 20 12320 2.8 3.8 37 14 embodiment Ni.sub.36.5Mn.sub.35Co.sub.13.5Ti.sub.15 The seventh 1200 9 8540 4.8 3.5 44.5 18 embodiment Ni.sub.35Mn.sub.35Co.sub.15Ti.sub.15 The eighth 980 35 15560 5.8 4.8 28 15 embodiment Ni.sub.57Mn.sub.14Co.sub.16Ti.sub.13 The ninth 1500 7 10540 4.9 3.0 50 15.5 embodiment Ni.sub.35Mn.sub.36.5Co.sub.10.5Ti.sub.18 The ninth 900 10 6350 3.3 5.1 20 20 embodiment Ni.sub.28Mn.sub.37Co.sub.12Ti.sub.23 The eleventh 1380 12 13350 7.5 4.2 31 12 embodiment Ni.sub.53Mn.sub.16Co.sub.14Ti.sub.17 Comparative 300 4 0 18 Example Ni.sub.2MnGa