碳添加引起一种超导高熵合金的中心对称到非中心对称结构转变  

Centrosymmetric to noncentrosymmetric structural transformation in a superconducting high-entropy alloy due to carbon addition

作　　者：肖国锐 祝钦清 杨武璋 崔艳威 宋世杰 曹光旱 任之 Guorui Xiao;Qinqing Zhu;Wuzhang Yang;Yanwei Cui;Shijie Song;Guang-Han Cao;Zhi Ren(School of Science,Westlake University,Hangzhou 310024,China;Institute of Natural Sciences,Westlake Institute for Advanced Study,Hangzhou 310024,China;Department of Physics,Zhejiang University,Hangzhou 310027,China;Department of Physics,Fudan University,Shanghai 200433,China)

机构地区：[1]School of Science,Westlake University,Hangzhou 310024,China [2]Institute of Natural Sciences,Westlake Institute for Advanced Study,Hangzhou 310024,China [3]Department of Physics,Zhejiang University,Hangzhou 310027,China [4]Department of Physics,Fudan University,Shanghai 200433,China

出　　处：《Science China Materials》2023年第1期257-263,共7页中国科学（材料科学（英文版）

基　　金：financial support by the foundation of Westlake University and the Service Center for Physical Sciences for technical assistance in SEM measurements;supported by the National Natural Science Foundation of China(12050003)。

摘　　要：四方σ相是过渡金属合金中最常见的物相之一.然而,σ型高熵合金中尚未有关于碳添加效应的报道.在本文中,我们发现在超导的Ta_(10)Mo_(5)W_(30)Re_(35)Ru_(20)高熵合金(Tc=4.87K)中添加碳会引起结构转变.结果表明在0≤x≤2时Ta_(10)Mo_(5)W_(30)Re_(35)Ru_(20)Cx高熵合金具有中心对称的σ型结构,但在16≤x≤20时转变为非中心对称的β-Mn型结构.转变后的β-Mn型高熵合金仍表现出体超导电性且具有更高的Tc(5.34 K)和接近泡利顺磁极限的上临界场.此外,该结构转变归因于碳添加引起价电子浓度的降低以及晶格畸变和混合熵的增加.我们的研究结果不仅提供了高熵合金中中心对称到非中心对称结构转变的罕见例子,而且夯实了非金属碳是调节高熵合金结构和物理性质的有效添加剂.The tetragonalσphase is one of the most frequently occurring phases in transition metal alloys.However,the effect of carbon addition inσtype high-entropy alloys(HEAs)has not been studied to date.Here we report the observation of structural transformation by adding carbon in the superconducting Ta_(10)Mo_(5)W_(30)Re_(35)Ru_(20)HEA(critical temperature Tc=4.87 K).It is found that the Ta_(10)Mo_(5)W_(30)Re_(35)-Ru_(20)CxHEA adopts the centrosymmetricσtype structure for 0≤x≤2,but transforms into the noncentrosymmetricβ-Mn type structure for 16≤x≤20.The transformedβ-Mn type HEA also displays bulk superconductivity with a higher Tcof5.34 K and an upper critical field approaching the Pauli paramagnetic limit.In addition,the structural transformation is attributed to the decrease in valence electron concentration as well as the increase in lattice distortion and mixing entropy due to carbon addition.Our results not only provide a rare example of centrosymmetric to noncentrosymmetric structural transformation in HEAs,but also consolidate that nonmetallic carbon is an effective additive for tuning the structure and physical properties of HEAs.

关 键 词：高熵合金 结构转变 中心对称 晶格畸变 混合熵 Σ相 价电子浓度 超导 

分 类 号：TG139[一般工业技术—材料科学与工程]