铂铑合金系基本力学性能的第一性原理研究

发布时间：2018-06-19 04:16

本文选题：铂 + 铑　；参考：《稀有金属》2015年03期

【摘要】：采用密度泛函理论和虚晶近似方法对铂铑合金系的结构和力学性能进行计算。给出了常用低Rh含量和鲜有相关研究报道的高Rh含量合金的晶格常数、弹性系数和体积模量(B)等。通过晶格常数计算了不同合金的密度,与实测结果基本一致。通过弹性系数和力学稳定性判据发现该合金系结构是稳定的。计算的合金杨氏模量(E),剪切模量(G)与实验结果接近。随Rh含量的增加,G,E均增加,但B,G/B和泊松比均减小。通过分析确定随Rh含量的增加,合金的拉伸曲线变陡,延伸率变小,塑性变形难度增加。基于位错应变能的计算结果,发现随着Rh含量的增加位错应变能也增加,但Rh含量低于40%(质量分数)时增速较快,高于40%后变缓,该关系与实测的Rh含量与硬度、抗拉强度的关系一致。通过判定材料塑脆转变的G/B比值与Rh含量的关系,发现以Rh含量为40%为界,小于该值时Rh含量增加比值下降迅速,说明合金脆性增加较快,高于40%后比值减小变缓,表明合金脆性增加变缓。综合分析后认为随Rh含量增加铂铑合金的变形抗力增加、延伸率下降,脆性增加,导致合金塑性加工难度增大,但该变化速度为先快后慢,大致以Rh含量等于40%为界。对于低Rh含量的铂铑合金可以进行大变形量冷加工,而高Rh含量的铂铑合金只有通过提高温度,从而降低材料的G和E值才能进行一定的塑性加工。
[Abstract]:The structure and mechanical properties of platinum-rhodium alloy system were calculated by density functional theory and virtual crystal approximation. The lattice constant, elastic coefficient and bulk modulus of high Rh content alloys with low Rh content and rarely reported in this paper are given. The density of different alloys is calculated by lattice constant, which is in good agreement with the measured results. The elastic coefficient and the criterion of mechanical stability show that the structure of the alloy system is stable. The calculated Young's modulus and shear modulus (G) are in agreement with the experimental results. With the increase of Rh content, the G / B and Poisson's ratio of BU G / B and Poisson's ratio were all increased, but both B / G / B and Poisson's ratio were decreased. The results show that with the increase of Rh content, the tensile curve of the alloy becomes steeper, the elongation becomes smaller and the plastic deformation becomes more difficult. Based on the calculated results of dislocation strain energy, it is found that with the increase of Rh content, the dislocation strain energy also increases, but when Rh content is lower than 40% (mass fraction), the growth rate of dislocation strain energy increases faster, and then slows down after 40%, which is related to the measured Rh content and hardness. The relationship between tensile strength and tensile strength is consistent. By judging the relationship between the ratio of G / B and the content of Rh, it is found that when the ratio of Rh is 40%, the increasing ratio of Rh content decreases rapidly, which indicates that the brittleness of the alloy increases more quickly, and the ratio decreases slowly when the ratio is higher than 40%. It shows that the brittleness of the alloy increases slowly. It is considered that with the increase of Rh content, the deformation resistance of Pt-Rh alloy increases, the elongation decreases and the brittleness increases, which leads to the increase of the plastic processing difficulty of the alloy. However, the change rate of the alloy is first fast and then slow, and the limit of Rh content is about 40%. The low Rh content Pt-Rh alloy can be cold-worked with large deformation, while the high Rh content Pt-Rh alloy can only reduce the G and E values of the material by increasing the temperature.
【作者单位】：昆明理工大学材料科学与工程学院;昆明贵金属研究所稀贵金属综合利用新技术国家重点实验室;
【基金】：国家自然科学基金项目(51267007,51461023,U0837601,51164015) 云南省自然科学基金项目(2010CD126,2012FB195) 云南省省院省校合作项目(2012IB002) 云南省创新团队项目(2012HC027) 昆明市创新团队项目(2012-01-01-A-R-07-0005)资助
【分类号】：TG146.33

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