摘要
为了探索Al_xCrFeNiTi系高熵合金组成成分和弹性性质的关系,结合固溶体特征参数和第一性原理计算,研究Al元素含量对Al_xCrFeNiTi (x=0, 0.5, 1, 2, 3, 4)合金结构和弹性性质的影响,并分析合金固溶体特征参数与弹性性质之间的关系.结果表明:Al_xCrFeNiTi系合金的价电子浓度随着Al含量的增加逐渐减小,合金在体心立方结构下的形成焓均低于面心立方结构,说明研究的Al_xCrFeNiTi系合金会形成单一的体心立方结构固溶体;合金的晶格常数和形成能力强弱随着Al含量的增加而增大,但合金的结构稳定性略有下降;当合金元素按照等原子比进行成分配比时,合金的原子尺寸差异最大; Al_xCrFeNiTi系合金中不同原子之间除了金属键结合外,还表现出一定的共价和离子键结合特征;对于Al_xCrFeNiTi系合金而言,随着热力学熵焓比的增大,合金体弹模量和韧性随之增大;随着合金混合焓的增加,合金在压缩方向的各向异性程度明显降低.热力学熵焓比和混合焓可作为Al_xCrFeNiTi系高熵合金成分设计的重要参数.
The effects of Al content on structure and elastic properties of Al_xCrFeNiTi(x = 0, 0.5, 1, 2, 3, 4), and elastic properties varying with solid solution characteristic parameters of alloys are investigated in this work to explore the relationships between compositions and elastic properties of Al_xCrFeNiTi high entropy alloys. The results show that the valence electron concentrations of Al_xCrFeNiTi alloys decrease gradually with the increase of Al content, and the enthalpy formed by alloy with body center cubic structure is lower than that with face center cubic structure when Al content of the alloy is the same. It implies that Al_xCrFeNiTi alloy will form a single solid solution with body centered cubic structure by referring to valence electron concentration theory and formation enthalpy calculation. The lattice constants and formation capacities of Al_xCrFeNiTi alloys increase with Al content rising, while the structure stability of alloys presents a gradual downward trend. The atomic size difference shows the largest value when all elements in the alloy have equal molar ratio, indicating that the lattice distortion of the alloy exhibits the highest level at this time. The total state of density of Al_xCrFeNiTi alloy moves to a higher energy level as the content of Al increases, which is an obvious characteristic of the declining structural stability of alloys. It is consistent with the result of cohesive energy. Al and Ti both lose electrons after bonding, while Ni and Fe both gain electrons. The bonding behavior between atoms shows not only metal bonding but also somewhat covalent and ionic bonding characteristics by analyzing the electron density difference and atomic Mulliken populations of Al_xCrFeNiTi alloys. The elastic modulus and toughness of alloy will be improved with the increase of the ratio of thermodynamic entropy to enthalpy( ?),and the anisotropy in compression direction of alloy decreases obviously with the rise of mixing enthalpy(ΔHmix). The solid solution characteristics including ? and ΔHmix will be used as important parameters for the compositions’ design for Al_xCrFeNiTi alloy.
作者
王浩玉
农智升
王继杰
朱景川
Wang Hao-Yu;Nong Zhi-Sheng;Wang Ji-Jie;Zhu Jing-Chuan(School of Materials Science and Engineering,Shenyang Aerospace University,Shenyang 110136,China;School of Materials Science and Engineering,Harbin Institute of Technology,Harbin 150001,China)
出处
《物理学报》
SCIE
EI
CAS
CSCD
北大核心
2019年第3期212-221,共10页
Acta Physica Sinica
基金
国家自然科学基金(批准号:51701128)资助的课题~~
