缺碳高熵碳化物(Ti_(_(0.2))Zr_(0.2)Hf_(0.2)Nb_(0.2)Ta_(0.2))C_(1-x)硬度的压痕载荷效应

The Indentation Load Effect of Hardness of Non-Stoichiometric High-Entropy Carbides(Ti_(_(0.2))Zr_(0.2)Hf_(0.2)Nb_(0.2)Ta_(0.2))C_(1-x)

本文研究了不同碳空位浓度下的缺碳高熵碳化物陶瓷(Ti_(_(0.2))Zr_(0.2)Hf_(0.2)Nb_(0.2)Ta_(0.2))C_(1-x)(HEC_(1-x),x=0~0.5)硬度的压痕尺寸效应(ISE)。实验结果表明,随着载荷从0.05kgf增加至1kgf,压痕尺寸快速增大,硬度迅速下降。并且,比例试样阻力(PSR)模型能够较好的描述本研究中缺碳高熵碳化物的压痕尺寸效应。HEC_(1-x)陶瓷的硬度随载荷增大逐渐降低,但其降低幅度随碳空位浓度的升高而先减小后增加,反映出HEC_(1-x)陶瓷的ISE效应随碳空位浓度增加而先减小后增大。HEC_(0.8)的硬度随载荷增加变化最小,其压痕尺寸效应最弱。根据载荷-压痕尺寸关系的拟合曲线计算得出HEC_(1-x)陶瓷的真实硬度随碳空位浓度的升高先增加后减少,在HEC_(0.9)处取得最大值为22.2 GPa。

This paper studied the indentation size effect(ISE)of non-stoichiometric high-entropy carbide ceramics(Ti_(_(0.2))Zr_(0.2)Hf_(0.2)Nb_(0.2)Ta_(0.2))C_(1-x)(HEC_(1-x),x=0~0.5)with different carbon vacancy concentration.The experimental results showed that the indentation size increased and the hardness decreased rapidly as the load increased from 0.05 kgf to 1 kgf.Moreover,the proportional specimen resistance(PSR)model can describe the indentation size effect of high-entropy carbides in this study.The hardness decreased gradually with the load rised,but the degree of change decreased first and then increased with the increase of carbon vacancy concentration,which revealed that the ISE in HEC_(1-x)system had the same trend of variation with the increase of carbon vacancy concentration.The hardness of HEC_(0.8)had the smallest change with the increase of load,indicating it had the weakest ISE.According to the fited polynomial curves of load-indentation size relationship,the true hardness of ceramics increased first and then decreased with the increase of carbon vacancy concentration,and the maximum value was 22.2 GPa at HEC_(0.9).