Outstanding specific yield strength of a refractory high-entropy composite at an ultrahigh temperature of 2273 K  

作　　者：Bo Sun Jinyong Mo Qianqian Wang Yongxiong Chen Zhibin Zhang Baolong Shen Xiubing Liang 

机构地区：[1]Defense Innovation Institute,Academy of Military Science,Beijing,100071,China [2]School of Materials Science and Engineering,Jiangsu Key Laboratory for Advanced Metallic Materials,Southeast University,Nanjing,211189,China

出　　处：《Journal of Materials Science & Technology》2023年第35期145-154,共10页材料科学技术（英文版）

基　　金：This work is supported by the National Key Research and Development Program of China(Grant No.2018YFC1902400);the National Natural Science Foundation of China(Grant No.51975582);the Key Research and Development Program of Jiangsu Province(Grant No.BE2021088).

摘　　要：We reported on the mechanical properties and microstructural evolution of a W_(20)Ta_(30)Mo_(20)C_(30)(at.%)re-fractory high-entropy composite(RHEC).The RHEC exhibited outstanding yield strength at both 2273 and 1873 K.Microstructural investigations revealed that the as-cast RHEC had a triple-phase structure con-sisting of FCC dendrites,HCP matrix,HCP-BCC eutectic structure,and FCC-BCC eutectoid structure,and exhibited high-density defects owing to the complex phase transformations during solidification.After annealing at 2273 K,the precipitation of the BCC phase from the FCC dendrites and the decomposition of the HCP phase into the FCC-BCC eutectoid structure was observed to significantly refine the grain sizes of all triple phases.After compression at 2273 K,the ceramic phases and solid solution precipitated out from each other,which helps to avoid persistent softening after the yielding of RHEC.Further analyses sug-gested that the dominant deformation mechanisms of the BCC phase and HCP phase are dislocation glide and transformation-induced plasticity;whereas those of the FCC phase are twinning-and transformation-induced plasticity.The outstanding yield strength of this RHEC at ultrahigh temperatures may originate from the high-content ceramic phases and the structural metastability of the multi-principal composition.These findings provide a novel strategy to design RHECs by alloying high-content nonmetallic elements,which contributes to further breaking through their performance limits at ultrahigh temperatures.

关 键 词：Refractory high-entropy composite METASTABILITY Ultrahigh temperature Mechanical property Phase transformation 

分 类 号：TG139[一般工业技术—材料科学与工程]