Unusual softening behavior of yield strength in niobium at high pressures  

作　　者：Qiu-Min Jing Qiang He Yi Zhang Shou-Rui Li Lei Liu Qi-Yue Hou Hua-Yun Geng Yan Bi Yu-Ying Yu Qiang Wu 敬秋民;何强;张毅;李守瑞;柳雷;侯琪玥;耿华运;毕延;俞宇颖;吴强(National Key Laboratory of Shock Wave and Detonation Physics,Institute of Fluid Physics,China Academy of Engineering Physics)

机构地区：National Key Laboratory of Shock Wave and Detonation Physics,Institute of Fluid Physics,China Academy of Engineering Physics,Mianyang 621900,China

出　　处：《Chinese Physics B》2018年第10期501-507,共7页中国物理B（英文版）

基　　金：Project supported by the National Natural Science Foundation of China(Grant Nos.U1530134,U1730248,11772312,and 11504354)

摘　　要：In situ synchrotron angle-dispersive x-ray diffraction experiments on niobium powders have been conducted at pressures up to 61 GPa and room temperature using the diamond anvil cell technique. From the full width at half maximum of the measured diffraction lines, the yield strength was derived with the line-width analysis theory. The niobium powder sample was found to be compressed more packed firstly and then yielded at~14 GPa–18 GPa. Following an initial increase in the yield strength with pressure, an obvious decrease was observed occurring at ~42 GPa–47 GPa accompanying with a typical pressure dependence above 47 GPa. The experimentally observed anomalous softening of the yield strength in niobium surprisingly follows the trend of the predicted unusual softening in the shear modulus by the recent theoretical investigations. The possible mechanisms, applicable to interpret the yield strength softening of materials at high pressure,were also discussed in detail.In situ synchrotron angle-dispersive x-ray diffraction experiments on niobium powders have been conducted at pressures up to 61 GPa and room temperature using the diamond anvil cell technique. From the full width at half maximum of the measured diffraction lines, the yield strength was derived with the line-width analysis theory. The niobium powder sample was found to be compressed more packed firstly and then yielded at^14 GPa–18 GPa. Following an initial increase in the yield strength with pressure, an obvious decrease was observed occurring at ~42 GPa–47 GPa accompanying with a typical pressure dependence above 47 GPa. The experimentally observed anomalous softening of the yield strength in niobium surprisingly follows the trend of the predicted unusual softening in the shear modulus by the recent theoretical investigations. The possible mechanisms, applicable to interpret the yield strength softening of materials at high pressure,were also discussed in detail.

关 键 词：x-ray diffraction NIOBIUM diamond anvil cell yield strength anomalous softening 

分 类 号：TG146.416[一般工业技术—材料科学与工程]