FCC-to-HCP Phase Transformation in CoCrNix Medium-Entropy Alloys
来源期刊：Acta Metallurgica Sinica2020年第8期
论文作者：Jia-Qi Zhao Hua Tian Zhong Wang Xue-Jiao Wang Jun-Wei Qiao
文章页码：1151 - 1158
摘 要：A hybrid first-principles/Monte Carlo simulation is combined with experiments to study the structure and elastic properties of CoCrNix（x=1-0.5） alloys.The experimental X-ray diffraction patterns show that the structures have changed from the single-phase face-centered cubic（FCC） structure at x=1-0.8 to the coexistence of FCC and the hexagonal close-packed structures at x=0.7-0.5,which is further confirmed by calculations on mixing energies.The elastic moduli by calculation are basically in agreement with experiments.Room-temperature tension shows that the six alloys have a certain plasticity,the strength and plasticity of the alloys have a linear decrease with the decrease in Ni contents,and the plasticity of the alloys drops from 84 to 23%.Furthermore,first-principles density function theory calculations were employed to reveal the electronic and magnetic structures of alloys.The electron density of states for all alloys is asymmetrical,which illustrates that the alloys are ferromagnetism.It is found that Cr atoms can suppress the ferromagnetism of alloys,since Cr atoms have both positive and negative magnetic moments in all alloys.
Jia-Qi Zhao1，Hua Tian2，Zhong Wang1，Xue-Jiao Wang1，Jun-Wei Qiao1
1. College of Materials Science and Engineering, Taiyuan University of Technology2. College of Information and Computer, Taiyuan University of Technology
摘 要：A hybrid first-principles/Monte Carlo simulation is combined with experiments to study the structure and elastic properties of CoCrNix（x=1-0.5） alloys.The experimental X-ray diffraction patterns show that the structures have changed from the single-phase face-centered cubic（FCC） structure at x=1-0.8 to the coexistence of FCC and the hexagonal close-packed structures at x=0.7-0.5,which is further confirmed by calculations on mixing energies.The elastic moduli by calculation are basically in agreement with experiments.Room-temperature tension shows that the six alloys have a certain plasticity,the strength and plasticity of the alloys have a linear decrease with the decrease in Ni contents,and the plasticity of the alloys drops from 84 to 23%.Furthermore,first-principles density function theory calculations were employed to reveal the electronic and magnetic structures of alloys.The electron density of states for all alloys is asymmetrical,which illustrates that the alloys are ferromagnetism.It is found that Cr atoms can suppress the ferromagnetism of alloys,since Cr atoms have both positive and negative magnetic moments in all alloys.
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