铼的弹性剪切参数C44对温度与压力响应的原位拉曼光谱研究

铼具有高体积弹性模量、高熔点、优良的抗蠕变性能，是一种重要科学研究与工程应用材料。铼的弹性剪切系数C₄₄对温度和压力的响应特性对铼及其合金材料的设计与工程应用具有重要意义。激光拉曼散射技术在研究不同温度和压力条件下六方密堆积结构(hcp)金属的弹性剪切系数C₄₄上具有独特的优势。但由于金属的强反射作用和浅的穿透深度，hcp金属的低波数拉曼散射信号往往很难获取，在一定的温度和压力加载下拉曼信号的获取尤为困难。利用侧向激发拉曼散射技术，有效降低了金属强反射对拉曼光谱采集的影响，成功测量到多晶铼在不同压力与温度条件下的E_2g拉曼振动模，获得铼在常温常压条件的弹性剪切系数(C₄₄=133 GPa)以及其弹性剪切系数C₄₄对温度和压力的响应特性。研究结果表明，多晶铼的弹性剪切系数C₄₄模量随压强的增加而增大，随温度的增加而减小。这也为用光散射方法研究金属材料剪切模量提供了良好研究方法。

Response of Elastic Shear Parameter C44 of Rhenium to Temperature and Pressure: A Raman Spectroscopy Study

Rhenium is an important material for research and engineering applications due to the high bulk modulus, high melting point and excellent creepresistance. Theresponse of the shear elastic constant C₄₄ of rhenium to temperature and pressure is important to the design and application of rhenium and its alloy. Raman scattering technique has unique advantages in studying the shear elastic constant C₄₄ of hexagonal closest packed (hcp) metal under different temperatures and pressures. However, it is difficult to obtain the signals of low wavenumber Raman scattering for hcp metals due tothe strong reflection and shallow penetration depth of metals, especiallyunder a certain temperature and pressure loading. In this work, the lateral-incidentRaman scattering technology was carried outtoreduce the influence of metal strong reflection on Raman spectra. Consequently, we successfully measured E_2g modes of polycrystallinerhenium under different pressure and temperature. The shear elastic constant C₄₄ is 133 GPa at ambient condition. And we obtainedthe response of the shear elastic constant C₄₄ of rhenium to temperature and pressure. The results show that the elastic shear coefficient C₄₄ of polycrystalline rhenium increases with the increase of the pressure, and decreases with the increase of temperature. And, this work proposes a good research method for the shear elastic constant of metal material with Raman scattering.