Hussain Syed Waqas, Mehmood M Adil, Karim M Ramzan Abdul, Godfrey Andy, Yaqoob Khurram
School of Chemical and Materials Engineering (SCME), National University of Sciences and Technology (NUST), H-12, Islamabad, Pakistan.
Department of Materials Science and Engineering, Ghulam Ishaq Khan Institute of Engineering Sciences and Technology, Topi, Swabi, 23640, KPK, Pakistan.
Sci Rep. 2022 Jun 14;12(1):9822. doi: 10.1038/s41598-022-13649-5.
High entropy alloys (HEAs) are a relatively new class of material that have shown the potential to exhibit excellent combinations of mechanical properties. Various microstructural modifications have been explored to further enhance their mechanical properties for use in demanding structural applications. The main focus of the present work is an investigation of the effect of adding varying amounts of hard ceramic material (WC) to a tough HEA matrix (CoCrFeNi) by arc melting under an argon atmosphere, including microstructural changes, and evaluation of the WC additions on mechanical properties. X-ray diffraction analysis of the HEA-WC composites showed the presence of both fcc and carbide phases. Scanning electron microscope investigations, including energy dispersive spectroscopy, reveal that chromium diffuses from the matrix and interacts with WC to form an alloyed carbide phase. The amount of alloyed carbide was found to increase with increasing amount of WC addition to the HEA matrix. Mechanical characterization revealed that hardness and yield strength of the HEA-WC composites increase with increasing amount of the carbide phase in the matrix. The hardness of HEA-20wt.% WC sample was found to be as high as 3.3 times (593 HV) the hardness of the base HEA (180 HV), while the yield strength increased from 278 MPa for the base HEA to 1098 MPa for the CoCrFeNi-20 wt.% WC composite. The investigated composites also showed excellent values of ductility (~ 50% strain for CoCrFeNi-10 wt% WC and ~ 20% strain for CoCrFeNi-20 wt% WC). It is therefore believed that ceramic-reinforced high entropy matrix composites have the potential to provide outstanding combinations of mechanical properties for demanding structural applications.
高熵合金（HEAs）是一类相对较新的材料，已显示出具有展现优异机械性能组合的潜力。人们已探索了各种微观结构改性方法，以进一步提高其机械性能，用于要求苛刻的结构应用。本工作的主要重点是研究在氩气气氛下通过电弧熔炼向韧性高熵合金基体（CoCrFeNi）中添加不同量的硬质陶瓷材料（WC）的效果，包括微观结构变化，以及评估WC添加量对机械性能的影响。对HEA-WC复合材料的X射线衍射分析表明存在面心立方相和碳化物相。扫描电子显微镜研究，包括能量色散光谱分析，揭示铬从基体中扩散出来并与WC相互作用形成合金碳化物相。发现合金碳化物的量随着向HEA基体中添加WC量的增加而增加。力学表征表明，HEA-WC复合材料的硬度和屈服强度随着基体中碳化物相含量的增加而增加。发现HEA-20wt.%WC样品的硬度高达基体HEA硬度（180 HV）的3.3倍（593 HV），而屈服强度从基体HEA的278 MPa增加到CoCrFeNi-20 wt.%WC复合材料的1098 MPa。所研究的复合材料还显示出优异的延展性值（CoCrFeNi-10 wt%WC的应变约为50%，CoCrFeNi-20 wt%WC的应变约为20%）。因此，人们认为陶瓷增强高熵基体复合材料有可能为要求苛刻的结构应用提供优异的机械性能组合。
