Zhou Junjie, Yang Yu, Yu Yinsheng
School of Mechanical and Power Engineering, Zhengzhou University, Zhengzhou, 450001, Henan, China.
J Mol Model. 2022 Nov 1;28(11):371. doi: 10.1007/s00894-022-05350-1.
In this study, the Ni/NiAl-based alloys were proposed, and their microstructures were established. Uniaxial tension was performed based on the γ' phase precipitates of alloys with different shape ratio by means of molecular dynamics (MD) simulations. We demonstrate that the crystal distortion induced by the transition from FCC to disordered structure can lead to the reduction of tensile strength. Besides, the structure, temperature, and strain rate effects on the mechanical properties were clarified, and the microscale mechanism was revealed. The results indicated that compared with Ni/NiAl structure with a γ' phase precipitate shape ratio of 1:1:1, the tensile strength of the structure with a shape ratio of 1:2:1 is smaller, and the mechanical property-strengthening effect is significantly determined by the structures of the γ' phase precipitates; besides, there is a clear secondary strengthening in the tensile process of Ni/NiAl structure with a γ' phase precipitate shape ratio of 2:1:2 due to the formation of disordered structures. The elastic modulus and tensile strength of the models with different γ' phase precipitates shape ratios all decrease with the increase of temperature, under the conditions of low strain rate; the tensile strength of the alloys decreases with the decrease of strain rate.
在本研究中，提出了镍/镍铝基合金，并确定了其微观结构。借助分子动力学（MD）模拟，基于不同形状比合金的γ'相析出物进行了单轴拉伸。我们证明，从面心立方（FCC）到无序结构的转变所引起的晶体畸变会导致拉伸强度降低。此外，阐明了结构、温度和应变速率对力学性能的影响，并揭示了微观尺度机制。结果表明，与γ'相析出物形状比为1:1:1的镍/镍铝结构相比，形状比为1:2:1的结构的拉伸强度较小，力学性能强化效果显著取决于γ'相析出物的结构；此外，由于无序结构的形成，γ'相析出物形状比为2:1:2的镍/镍铝结构在拉伸过程中存在明显的二次强化。在低应变速率条件下，不同γ'相析出物形状比模型的弹性模量和拉伸强度均随温度升高而降低；合金的拉伸强度随应变速率降低而降低。
