Radiation resistant high-entropy alloy having FCC structure and preparation method thereof

Abstract

A radiation resistant high-entropy alloy is provided, having an FCC structure, defined by general formula of FeCoNiVMoTi.sub.xCr.sub.y, where 0.05≤x≤0.2, 0.05≤y≤0.3, x and y are molar ratios. The radiation resistant high-entropy alloy has excellent irradiation resistance and is subject to radiation hardening saturation at high temperature (600° C.) in a condition of a high dose (1-3×10.sup.16 ions/cm.sup.2) of helium ion irradiation. A lattice constant of the high-entropy alloy decreases abnormally after irradiation. The high-entropy alloy has a radiation resistance far higher than that of a conventional alloy and has an excellent plasticity and specific strength. In an as-cast condition and at room temperature, a tensile break strength of the high-entropy alloy is higher than 580 MPa, an engineering strain (a tensile elongation) of the high-entropy alloy is greater than 30%.

Claims

1. A radiation resistant high-entropy alloy having an FCC structure, defined by a general formula of Fe.sub.1Co.sub.1Ni.sub.1V.sub.1Mo.sub.1Ti.sub.xCr.sub.y, wherein 0.1≤x≤0.15, and 0.1≤y≤0.2, and a subscript of each element in the general formula represents a molar ratio.

2. The radiation resistant high-entropy alloy having an FCC structure of claim 1, wherein the radiation resistant high-entropy alloy is integrated in fuel cladding materials in nuclear power plant reactors and/or components of reactor cores of a nuclear power plant.

3. A method of producing a radiation resistant high-entropy alloy having an FCC structure, comprising: stacking Fe, Co, Ni, V, Mo, Ti, and Cr according to a proportion, and conducting vacuum levitation melting or vacuum arc melting, to obtain the radiation resistant high-entropy alloy having an FCC structure, wherein the radiation resistant high-entropy alloy having an FCC structure produced is defined by a general formula of Fe.sub.1Co.sub.1Ni.sub.1V.sub.1Mo.sub.1Ti.sub.xCr.sub.y, wherein 0.1≤x≤0.15, 0.1≤y≤0.2, and a subscript of each element in the general formula represents a molar ratio.

4. The method of claim 3, wherein the step of vacuum levitation melting or vacuum arc melting comprises: during fusion alloying, placing Ti, Fe, Co, and Ni at the bottom, and placing Mo, Cr, and V at the top.

5. The method of claim 3, wherein in the vacuum levitation melting or vacuum arc melting, vacuumizing is conducted to reach 5×10.sup.−3 Pa to 3×10.sup.−3 Pa, and back-filing with argon gas is conducted to reach 0.03 MPa to 0.05 MPa.

6. The method of claim 3, wherein alloy ingots are turned and melted five to seven times during the vacuum arc melting.

7. The method of claim 3, wherein alloy ingots are turned and melted four to six times during the vacuum levitation melting.

8. The method of claim 3, wherein Fe, Co, Ni, V, Mo, Ti, and Cr are all industrial grade pure raw materials with a purity of over 99.5 wt. %.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Various additional features and advantages of the invention will become more apparent to those of ordinary skill in the art upon review of the following detailed description of one or more illustrative embodiments taken in conjunction with the accompanying drawings. The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate one or more embodiments of the invention and, together with the general description given above and the detailed description given below, explain the one or more embodiments of the invention.

(2) FIG. 1 is a graphical plot showing relationships between average nano-indentation hardness and indentation depths at 600° C. before and after irradiation according to a first embodiment, where three different doses of irradiation are 5×10.sup.15 ions/cm.sup.2, 1×10.sup.16 ions/cm.sup.2, and 3×10.sup.16 ions/cm.sup.2.

(3) FIG. 2 is a graphical plot showing a relationship between a hardness change rate and an ion implantation amount of a radiation resistant high-entropy alloy having an FCC structure at 600° C. according to the first embodiment.

(4) FIG. 3 is a graphical plot showing XRD diffraction analysis patterns of a radiation resistant high-entropy alloy having an FCC structure before and after irradiation experiments according to the first embodiment, where once again, three different doses of irradiation are 5×10.sup.15 ions/cm.sup.2, 1×10.sup.16 ions/cm.sup.2, and 3×10.sup.16 ions/cm.sup.2.

(5) FIG. 4 is a graphical plot of a variation trend of a lattice constant of a radiation resistant high-entropy alloy having an FCC structure as an irradiation dose changes according to the first embodiment.

(6) FIG. 5 is a graphical plot of an engineering strain curve of a radiation resistant high-entropy alloy having an FCC structure at room temperature according to the first embodiment.

DETAILED DESCRIPTION

(7) The following clearly and completely describes the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. To make objectives, features, and advantages of the present invention clearer, the following describes embodiments of the present invention in more detail with reference to the accompanying drawing and specific implementations.

Embodiment 1

(8) This first embodiment provides a radiation resistant high-entropy alloy Fe—Co—Ni—V—Mo—Ti—Cr having an FCC structure, defined by a general formula of FeCoNiVMoTi.sub.0.1Cr.sub.0.1.

(9) A specific preparation method of FeCoNiVMoTi.sub.0.1Cr.sub.0.1 includes: stacking raw materials Fe, Co, Ni, V, Mo, Ti, and Cr according to a molar ratio shown by the general formula, where Fe, Co, Ni, V, Mo, Ti, and Cr are all industrial grade pure raw materials with a purity of over 99.5 wt. %; conducting vacuum arc melting or vacuum levitation melting; during fusion alloying, placing Ti, Fe, Co, and Ni at the bottom, and placing Mo, Cr, and V at the top; and conducting vacuumizing to reach 5×10.sup.−3 Pa, and back-filing with argon gas to 0.05 MPa. Each alloy ingot is melted at least five times during arc melting, to ensure composition uniformity.

(10) FIG. 1 shows relationships between average nano-indentation hardness and indentation depths at 600° C. before and after irradiation according to this embodiment. It can be learned from the figure that, compared with a conventional alloy, the alloy in the present invention is subject to radiation hardening saturation during radiation, but the damage is not increased as the radiation increases, and the alloy has excellent irradiation resistance. FIG. 2 shows a relationship between a hardness change rate and an ion implantation amount of a radiation resistant high-entropy alloy having an FCC structure at 600° C. according to this embodiment. A radiation hardening degree of a radiation resistant high-entropy alloy sample having an FCC structure in this embodiment increases as a radiation dose increases, and is subject to radiation hardening saturation when a high dose (1-3×10.sup.16 ions/cm.sup.2) of helium ions are implanted.

(11) FIG. 3 shows XRD diffraction analysis patterns of the radiation resistant high-entropy alloy FeCoNiVMoTi.sub.0.1Cr.sub.0.1 having an FCC structure before and after irradiation experiments according to this embodiment, and shows that the alloy is formed by an FCC structural phase both before and after irradiation experiments, is not subject to a phase change or does not produce a precipitated phase. The irradiation-resistant high entropy alloy in this embodiment has excellent irradiation stability. FIG. 4 shows a variation trend of a lattice constant of a radiation resistant high-entropy alloy having an FCC structure as an irradiation dose changes according to this embodiment. FIG. 3 and FIG. 4 show that a lattice constant of the alloy after irradiation decreases, while a lattice constant of a conventional alloy after irradiation increases, and therefore an irradiation behavior of the alloy is quite different from that of the conventional alloy.

(12) An alloy irradiation experiment process may be conducted as follows: First, a sample of the irradiation resistant high-entropy alloy having an FCC structure in this embodiment is cut into slices with a thickness of 1 mm (10 mm×6.5 mm) for double-sided fine grinding and single-side polishing. Then, a test sample is placed in an aqueous solution containing 50% H.sub.2SO.sub.4 and 40% glycerol for electropolishing at a voltage of 36V for 10 seconds; and is subject to ultrasonic cleaning with acetone, anhydrous ethanol, and deionized water. An irradiation experiment is conducted on the prepared sample at 600° C., where helium ion irradiation with energy of 3 MeV is adopted, and irradiation doses are 5×10.sup.15 ions/cm.sup.2, 1×10.sup.16 ions/cm.sup.2, and 3×10.sup.16 ions/cm.sup.2, respectively.

(13) FIG. 5 shows an engineering strain curve of a radiation resistant high-entropy alloy having an FCC structure at room temperature according to this embodiment, and shows excellent mechanical properties of the alloy.

Embodiment 2

(14) This second embodiment provides a radiation resistant high-entropy alloy having an FCC structure, defined by a general formula of FeCoNiVMoTi.sub.0.15Cr.sub.0.15. A preparation method of the radiation resistant high-entropy alloy in this embodiment is the same as that in Embodiment 1, described above.

(15) It is detected that FeCoNiVMoTi.sub.0.15Cr.sub.0.15 is in this embodiment and FeCoNiVMoTi.sub.0.1Cr.sub.0.1 in Embodiment 1 both have excellent mechanical properties and radiation resistance, and can be widely applied to fuel cladding materials in nuclear power plant reactors or metal components of reactor cores of the nuclear power plant.

(16) The present invention is not limited to description of the radiation resistant high-entropy alloy according to either exemplary embodiment described herein. To this end, changes in x and y and modifications made to the preparation method all fall within the protection scope of the present invention.

(17) The embodiments described above are only descriptions of preferred embodiments of the present invention, and are not intended to limit the scope of the present invention. Various variations and modifications can be made to the technical solution of the present invention by those of ordinary skills in the art, without departing from the design of the present invention. The variations and modifications should all fall within the claimed scope defined by the claims of the present invention.