Biocompatible Ti-based metallic glass for additive manufacturing

Abstract

A biocompatible Ti-based alloy having a formula of Ti.sub.aZr.sub.wTa.sub.bSi.sub.xSn.sub.yCo.sub.z is disclosed, wherein a is 40-44, b is 1-5 and the sum of w, x, y, z is 55. The alloy is amorphous. The alloy is applicable to manufacturing ultrafine powder which is used for additive manufacturing. The alloy is characterized in high glass forming ability, low toxicity, and high strength, and the powder thereof has low roughness and high circularity, and is suitable for implantable medical device.

Claims

1. A biocompatible Ti-based alloy, which is formed of an alloy having a formula of Ti.sub.aZr.sub.wTa.sub.bSi.sub.xSn.sub.yCo.sub.z, wherein a is 40-44; b is 1-5; a sum of w, x, y and z is 51-59; and at least one of y and z is not 0.

2. The Ti-based alloy of claim 1, wherein a is 41.5-42.5, and b is 2.5-3.5.

3. The Ti-based alloy of claim 2, wherein w is 22-48; x is 1-15; y is 1-15; and z is 1-23.

4. The Ti-based alloy of claim 1, wherein the Ti-based alloy is selected from the group consisting of Ti.sub.42Zr.sub.35Ta.sub.3Si.sub.5Co.sub.12.5Sn.sub.2.5, Ti.sub.42Zr.sub.35Ta.sub.3Si.sub.5Co.sub.10Sn.sub.5, Ti.sub.42Zr.sub.35Ta.sub.3Si.sub.5Co.sub.7.5Sn.sub.7.5, Ti.sub.42Zr.sub.35Ta.sub.3Si.sub.5Co.sub.5Sn.sub.10, Ti.sub.42Zr.sub.35Ta.sub.3Si.sub.5Co.sub.2.5Sn.sub.12.5, Ti.sub.42Zr.sub.35Ta.sub.3Si.sub.6.25Sn.sub.2.5Co.sub.11.25, Ti.sub.42Zr.sub.35Ta.sub.3Si.sub.6.25Sn.sub.1.25Co.sub.12.5, Ti.sub.42Zr.sub.35Ta.sub.3Si.sub.5Sn.sub.3.75Co.sub.11.25, Ti.sub.42Zr.sub.35Ta.sub.3Si.sub.5Sn.sub.1.25Co.sub.13.75, Ti.sub.42Zr.sub.35Ta.sub.3Si.sub.3.75Sn.sub.5Co.sub.11.25, Ti.sub.42Zr.sub.35Ta.sub.3Si.sub.3.75Sn.sub.3.75Co.sub.12.5, Ti.sub.42Zr.sub.35Ta.sub.3Si.sub.3.75Sn.sub.2.5Co.sub.13.75, Ti.sub.42Zr.sub.35Ta.sub.3Si.sub.2.5Sn.sub.6.25Co.sub.11.25, Ti.sub.42Zr.sub.35Ta.sub.3Si.sub.2.5Sn.sub.5Co.sub.12.5, Ti.sub.42Zr.sub.35Ta.sub.3Si.sub.2.5Sn.sub.3.75Co.sub.13.75, Ti.sub.42Zr.sub.35Ta.sub.3Si.sub.2.5Sn.sub.2.5Co.sub.15, Ti.sub.42Zr.sub.35Ta.sub.3Si.sub.1.25Sn.sub.6.25Co.sub.12.5, Ti.sub.42Zr.sub.35Ta.sub.3Si.sub.1.25Sn.sub.5Co.sub.13.75, Ti.sub.42Zr.sub.35Ta.sub.3Si.sub.1.25Sn.sub.3.75Co.sub.15, Ti.sub.42Zr.sub.35Ta.sub.3Si.sub.0Sn.sub.3.75Co.sub.16.25, and Ti.sub.42Zr.sub.35Ta.sub.3Si.sub.2.5Sn.sub.1.25Co.sub.16.25.

5. The Ti-based alloy of claim 1, wherein the Ti-based alloy is an amorphous alloy.

6. The Ti-based alloy of claim 1, wherein the Ti-based alloy has a melting point below 1000 C.

7. The Ti-based alloy of claim 1, wherein the Ti-based alloy is suitable for additive manufacturing.

8. The Ti-based alloy of claim 7, wherein the Ti-based alloy is in a form of glass ultrafine powders formed by atomization using argon.

9. The Ti-based alloy of claim 8, wherein at least half of the glass ultrafine powders have a particle size below 53 m.

10. The Ti-based alloy of claim 8, wherein the glass ultrafine powder has a form factor of 0.85-1.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The sole FIGURE shows the particle-size distribution of the powders of the TiSnCoTi-based alloy system suitable for additive manufacturing.

[0019] 7

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

[0020] The invention as well as a preferred mode of use, further objectives and advantages thereof will be best understood by reference to the following detailed description of illustrative embodiments when read in conjunction with the accompanying drawings.

[0021] Unless stated otherwise in the specification, throughout the specification of the present invention and the appended claims, all the technical and scientific terms referred have the definitions as those known to people of ordinary skill in the art. When used related to any element or feature, the terms a, an, the or the like shall refer to more than one that element or feature, unless stated otherwise in the specification. In the present specification, where any of the terms ofor, and, and as well as is used, it actually means and/or, unless stated otherwise in the specification. In addition, the terms comprising and including are both in the nature of open ended transition and represents no exclusiveness. The foregoing definitions are only for illustrative purposes and shall form no limitation to the subject matter of the present invention. Unless stated otherwise in the specification, materials used in the present invention are all commercial available.

[0022] For testing properties of different Ti-based alloys having different compositions, alloys of different Ti.sub.aZr.sub.wTa.sub.bSi.sub.xSn.sub.yCo.sub.z compositions are taken as subjects, where 40a44, 1b5, and the sum of w, x, y, and z is 55, in which at least one of y and z is not 0. Preferably, a is 42, and b is 3. Therein, the factors a, b, w, x, y, and z each represent an atomic percentage (at %) of a particular metal in each unit of the alloy. The foregoing alloys are repeatedly melted into alloy ingots in an electric arc furnace under protection of argon gas, and then the alloy ingots are input into a ribbon maker to be made into long metallic glass ribbons having a thickness of 25-50 m using a melt spinning process.

[0023] By using x-rays and a transmission electron microscope (TEM), it is verified that the made ribbons have their microstructure as amorphous alloys. Afterward, a scanning electron microscope (SEM)/energy dispersive x-ray spectroscopy (EDS) and an electron probe x-ray microanalyzer (EPMA) are used to identify whether there is any differences between the designed composition and the actual composition after smelting for each of the alloys. As it is certained that there is no difference, the ribbons are analyzed using differential scanning calorimetry (DSC) and high-temperature DSC to identify its glass transition temperature (T.sub.g) (calculated using the absolute temperature), crystallization temperature (T.sub.x), melting temperature (T.sub.m), and liquid phase temperature (T.sub.l). Then the relevant parameters are applied to indexes for glass forming ability, and the glass forming ability of each alloy compositions is calculated. The aforementioned indexes include:

T.sub.rg=T.sub.g/T.sub.l;

T.sub.x=T.sub.xT.sub.g;

=T.sub.x/(T.sub.g+T.sub.l); and

.sub.m=(2T.sub.xT.sub.g)/T.sub.l.

COMPARATIVE EXAMPLE

[0024] As seen in the references, the existing biomedical implants made of porous, amorphous alloys are all constant in terms of porosity, which is not the same as the structure of human bones. Instead, a bionic implant has a supportive outer layer with relatively compact texture, and an inner layer having progressive arrangement of porosity to allow human texture and body fluid to flow therethrough. Such a complicated geometry can never be made by traditional processing method without using additive manufacturing. The present invention thus aims at providing a powder material that is suitable for being atomized and sprayed as required by additive manufacturing, and that, after subjected to laser sintering, has its microstructure of a metallic glass state.

[0025] The Ti.sub.42ZrTa.sub.3Si alloy system currently used in the art contains a certain proportion of Si. However, Si has the smallest atomic size in the alloy, and a high Si content leads to high packing density. On the contrary, reducing the proportion of Si is effective in decreasing the alloy's liquid viscosity.

[0026] The properties of the Ti.sub.42ZrTa.sub.3Si alloy system are shown in Table 1.

TABLE-US-00001 TABLE 1 T.sub.m T.sub.l T.sub.m T.sub.g T.sub.x T.sub.x T.sub.rg .sub.m Ti.sub.42Zr.sub.40Ta.sub.3Si.sub.15 1620 1751 131 799 879 80 0.456 0.548 0.345 Ti.sub.43Zr.sub.41Ta.sub.3Si.sub.12.5 1623 1743 120 766 893 127 0.439 0.585 0.356

[0027] The Ti.sub.42ZrTa.sub.3Si alloy system has disadvantages related to high viscosity and poor glass forming ability, among others. In order to provide powders suitable for the spraying process in additive manufacturing, the alloy is preferred to have high glass forming ability and low viscosity. However, as reflected in the comparative example shown in Table 1, the content of Si must be 12.5% or more. Thus, the addition of other elements is required for the desired properties.

Embodiment 1

[0028] An TiZrTaSi alloy is used as the substrate with Sn and Co added therein, and is tested for its properties. The properties of the alloy of the present embodiment as tested are shown in Tables 2-4.

TABLE-US-00002 TABLE 2 Alloy of TiSn System T.sub.m T.sub.l T.sub.m T.sub.g T.sub.x T.sub.x T.sub.rg .sub.m Ti.sub.42Zr.sub.42Ta.sub.3Si.sub.5Sn.sub.8 1638 1732 94 815 923 108 0.471 0.595 0.362 Ti.sub.42Zr.sub.42Ta.sub.3Si.sub.7.5Sn.sub.5.5 1616 1709 93 763 900 137 0.446 0.607 0.364 Ti.sub.42Zr.sub.42Ta.sub.3Si.sub.10Sn.sub.3 1617 1703 86 751 900 149 0.441 0.616 0.367 Ti.sub.42Zr.sub.40Ta.sub.3Si.sub.7.5Sn.sub.7.5 1618 1738 120 776 904 128 0.446 0.594 0.360 Ti.sub.42Zr.sub.40Ta.sub.3Si.sub.10Sn.sub.5 1611 1728 117 773 910 137 0.447 0.606 0.364 Ti.sub.42Zr.sub.40Ta.sub.3Si.sub.12.5Sn.sub.2.5 1610 1719 109 799 925 126 0.465 0.611 0.367 Ti.sub.42Zr.sub.37.5Ta.sub.3Si.sub.7.5Sn.sub.10 1625 1727 102 852 923 71 0.493 0.576 0.358 Ti.sub.42Zr.sub.37.5Ta.sub.3Si.sub.10Sn.sub.7.5 1622 1733 111 875 928 53 0.505 0.566 0.356 Ti.sub.42Zr.sub.35Ta.sub.3Si.sub.15Sn.sub.5 1625 1730 105 896 926 30 0.518 0.553 0.353 Ti.sub.40Zr.sub.42Ta.sub.3Si.sub.7.5Sn.sub.7.5 1613 1715 102 851 938 87 0.496 0.598 0.366

TABLE-US-00003 TABLE 3 Alloy of TiCo System T.sub.m T.sub.l T.sub.m T.sub.g T.sub.x T.sub.x T.sub.rg .sub.m Ti.sub.42Zr.sub.30Ta.sub.3Si.sub.15Co.sub.10 1132 1226 94 794 818 24 0.648 0.687 0.405 Ti.sub.42Zr.sub.32.5Ta.sub.3Si.sub.12.5Co.sub.10 1134 1189 55 796 833 37 0.669 0.732 0.420 Ti.sub.42Zr.sub.35Ta.sub.3Si.sub.10Co.sub.10 1130 1191 61 798 844 46 0.670 0.747 0.424 Ti.sub.42Zr.sub.27.5Ta.sub.3Si.sub.15Co.sub.12.5 1139 1240 101 776 808 32 0.626 0.677 0.401 Ti.sub.42Zr.sub.30Ta.sub.3Si.sub.12.5Co.sub.12.5 1136 1210 74 778 813 35 0.643 0.701 0.409 Ti.sub.42Zr.sub.32.5Ta.sub.3Si.sub.10Co.sub.12.5 1137 1212 75 771 822 51 0.636 0.720 0.415 Ti.sub.42Zr.sub.35Ta.sub.3Si.sub.7.5Co.sub.12.5 1134 1199 65 758 826 68 0.632 0.746 0.422 Ti.sub.42Zr.sub.37.5Ta.sub.3Si.sub.5Co.sub.12.5 1131 1201 70 781 850 69 0.650 0.765 0.429 Ti.sub.42Zr.sub.25Ta.sub.3Si.sub.15Co.sub.15 1143 1303 799 824 25 0.613 0.652 0.392 Ti.sub.42Zr.sub.27.5Ta.sub.3Si.sub.12.5Co.sub.15 1143 1201 58 779 817 38 0.649 0.712 0.413 Ti.sub.42Zr.sub.30Ta.sub.3Si.sub.10Co.sub.15 1139 1216 67 772 818 47 0.635 0.711 0.411 Ti.sub.42Zr.sub.32.5Ta.sub.3Si.sub.7.5Co.sub.15 1139 1220 81 777 834 57 0.637 0.730 0.418 Ti.sub.42Zr.sub.35Ta.sub.3Si.sub.5Co.sub.15 1131 1201 70 745 817 72 0.620 0.740 0.420 Ti.sub.42Zr.sub.22.5Ta.sub.3Si.sub.15Co.sub.17.5 1143 1386 243 814 Ti.sub.42Zr.sub.25Ta.sub.3Si.sub.12.5Co.sub.17.5 1143 1234 91 808 830 22 0.655 0.690 0.406 Ti.sub.42Zr.sub.27.5Ta.sub.3Si.sub.10Co.sub.17.5 1133 1224 91 799 832 33 0.653 0.707 0.411 Ti.sub.42Zr.sub.30Ta.sub.3Si.sub.7.5Co.sub.17.5 1138 1228 90 783 833 50 0.638 0.719 0.414 Ti.sub.42Zr.sub.32.5Ta.sub.3Si.sub.5Co.sub.17.52C 1136 1223 87 760 831 71 0.621 0.738 0.419 Ti.sub.42Zr.sub.25Ta.sub.3Si.sub.10Co.sub.20 1140 1291 151 805 841 36 0.624 0.679 0.401 Ti.sub.42Zr.sub.30Ta.sub.3Si.sub.5Co.sub.20 1132 1292 160 794 852 58 0.615 0.704 0.408 Ti.sub.42Zr.sub.15Ta.sub.3Si.sub.15Co.sub.25 1558 857 Ti.sub.42Zr.sub.20Ta.sub.3Si.sub.10Co.sub.25 1265 822 855 33 0.650 0.702 0.410

TABLE-US-00004 TABLE 4 Alloy of TiSnCo System T.sub.m T.sub.l T.sub.m T.sub.g T.sub.x T.sub.x T.sub.rg .sub.m Ti.sub.42Zr.sub.35Ta.sub.3Si.sub.5Co.sub.12.5Sn.sub.2.5 1142 1210 68 761 842 81 0.629 0.763 0.427 Ti.sub.42Zr.sub.35Ta.sub.3Si.sub.5Co.sub.10Sn.sub.5 1144 1212 68 809 873 64 0.667 0.773 0.432 Ti.sub.42Zr.sub.35Ta.sub.3Si.sub.5Co.sub.7.5Sn.sub.7.5 1144 1198 54 803 874 71 0.670 0.789 0.437 Ti.sub.42Zr.sub.35Ta.sub.3Si.sub.5Co.sub.5Sn.sub.10 1202 812 876 64 0.676 0.782 0.435 Ti.sub.42Zr.sub.35Ta.sub.3Si.sub.5Co.sub.2.5Sn.sub.12.5 1685 1706 21 848 873 25 0.497 0.526 0.342

TABLE-US-00005 TABLE 5 Alloy of TiSnCo System (with little Sn) T.sub.m T.sub.l T.sub.m T.sub.g T.sub.x T.sub.x T.sub.rg .sub.m Ti.sub.42Zr.sub.35Ta.sub.3Si.sub.6.25Sn.sub.2.5Co.sub.11.25 1142 1216 74 795 860 65 0.654 0.761 0.428 Ti.sub.42Zr.sub.35Ta.sub.3Si.sub.6.25Sn.sub.1.25Co.sub.12.5 1138 1204 66 781 848 67 0.649 0.760 0.427 Ti.sub.42Zr.sub.35Ta.sub.3Si.sub.5Sn.sub.3.75Co.sub.11.25 1141 1207 66 766 854 88 0.635 0.780 0.433 Ti.sub.42Zr.sub.35Ta.sub.3Si.sub.5Sn.sub.1.25Co.sub.13.75 1141 1211 70 838 892 54 0.692 0.781 0.435 Ti.sub.42Zr.sub.35Ta.sub.3Si.sub.3.75Sn.sub.5Co.sub.11.25 1139 1202 63 791 869 78 0.658 0.788 0.436 Ti.sub.42Zr.sub.35Ta.sub.3Si.sub.3.75Sn.sub.3.75Co.sub.12.5 1141 1204 63 770 860 90 0.640 0.789 0.436 Ti.sub.42Zr.sub.35Ta.sub.3Si.sub.3.75Sn.sub.2.5Co.sub.13.75 1139 1212 73 764 852 88 0.630 0.776 0.431 Ti.sub.42Zr.sub.35Ta.sub.3Si.sub.2.5Sn.sub.6.25Co.sub.11.25 1144 1204 60 794 876 82 0.659 0.796 0.438 Ti.sub.42Zr.sub.35Ta.sub.3Si.sub.2.5Sn.sub.5Co.sub.12.5 1145 1204 59 792 876 84 0.658 0.797 0.439 Ti.sub.42Zr.sub.35Ta.sub.3Si.sub.2.5Sn.sub.3.75Co.sub.13.75 1146 1214 68 776 866 90 0.639 0.787 0.435 Ti.sub.42Zr.sub.35Ta.sub.3Si.sub.2.5Sn.sub.2.5Co.sub.15 1146 1211 65 754 858 104 0.623 0.794 0.437 Ti.sub.42Zr.sub.35Ta.sub.3Si.sub.1.25Sn.sub.6.25Co.sub.12.5 1139 1203 64 802 892 90 0.667 0.816 0.445 Ti.sub.42Zr.sub.35Ta.sub.3Si.sub.1.25Sn.sub.5Co.sub.13.75 1147 1209 62 777 888 111 0.643 0.826 0.447 Ti.sub.42Zr.sub.35Ta.sub.3Si.sub.1.25Sn.sub.3.75Co.sub.15 1141 1207 66 780 884 104 0.646 0.819 0.445 Ti.sub.42Zr.sub.35Ta.sub.3Si.sub.0Sn.sub.3.75Co.sub.16.25 1145 1205 60 766 876 110 0.636 0.818 0.444 Ti.sub.42Zr.sub.35Ta.sub.3Si.sub.2.5Sn.sub.1.25Co.sub.16.25 1133 1202 69 735 848 113 0.611 0.800 0.438
As shown in Table 2, where the TiZrTaSi alloy is used as the substrate, with 2.5-10 atomic percent of Sn added therein, its T.sub.x is of 30-149, and its .sub.m is roughly of 0.5-0.61. As compared to the addition of 10% of Sn, the addition of 5% of Sn is more helpful to decrease the value of T.sub.x.

[0029] In addition, as shown in Table 3, where the TiZrTaSi alloy is used as the substrate, with 7-17.5 atomic percent of Co added therein, its T.sub.x is of 22-72, and its .sub.m is roughly of 0.65-0.76. By comparing Sn and Co in terms of glass forming ability, it is learned that the addition of Co does improve the alloy's glass forming ability. Thus, it is envisaged that an alloy with preferred glass forming ability can be made by using the TiZrTaSi alloy as the substrate, and adding Sn or Co at a certain mole ratio.

[0030] Additionally, as shown in Table 4, where the TiZrTaSi alloy is used as the substrate, with 2.5-12.5 atomic percent of Co and 2.5-12.5 atomic percent of Sn added therein, its .sub.m is as high as more than 0.76. Thus, a Ti-based alloy may be improved in terms of glass forming ability by mixing Co and Sn in a specific proportion therein.

[0031] Besides, as shown in Table 5, where the TiZrTaSi-based alloy is used as the substrate, with Sn or Co added therein following a specific proportion, and is further tested for the positive impact of the addition of Sn in a mole ratio below 6.25 on its glass forming ability, the value of .sub.m is at least 0.78. In another preferred embodiment, the value of .sub.m is as high as 0.8-0.82.

[0032] The biocompatible Ti-based alloy suitable for additive manufacturing preferably has low viscosity, low melting point, and good glass forming ability (GFA). An alloy having low melting point usually has good glass forming ability, and the low melting point means that low power laser is sufficient for working with it. In the embodiments of the present invention, while the addition of Sn effectively decreases the alloy's viscosity and enhances the alloy's glass forming ability, it has no effect on the alloy's melting point, yet increases the value of T.sub.x. On the other hand, the addition of Co effectively reduces the alloy's viscosity, melting point, and T.sub.x, and is favorable to the alloy's glass forming ability.

Embodiment 2

[0033] Since the Ti-based alloy has high metallic glass viscosity that is unfavorable to powder spraying, the present invention provides another method for making powders of the Ti-based alloy of Embodiment 1 for spraying. The resulting powders are suitable for additive manufacturing and feature for low surface roughness and high circularity.

[0034] Referring to the alloy as described herein related to Embodiment 1, Ti.sub.42Zr.sub.40Ta.sub.3Si.sub.7.5Sn.sub.7.5 is used to make powders for spraying. The method comprises: placing alloy ingots in a crucible, and heating the alloy ingots into liquid phase using radio frequency; transferring the liquid-phase alloy into a heat-insulating crucible, and pressurizing the heat-insulating crucible so that the liquid phase alloy in the heat-insulating crucible flows into a zone of atomizing spray nozzles in the heat-insulating crucible; and performing atomization using argon (Ar) on the liquid phase alloy coming out of the zone of the atomizing spray nozzles, so as to obtain the powders of the alloy.

[0035] The foregoing alloy powders are fine in terms of particle size, and have low surface roughness, thereby presenting desired flowability for powder-spreading and powder bed density, which are suitable for additive manufacturing. The alloy powders made using the foregoing method have their particle-size distribution shown in the sole FIGURE. For the TiSnCo alloy system, the proportion of powders having a particle diameter below 37 m is 26%, the proportion of powders having a particle diameter of 37-53 m is 25.7%, and the proportion of powders having a particle diameter below 53 m is 51.7%.