碳化物弥散强化高熵合金的耐磨性、硬度和显微组织

Wear resistance,hardness,and microstructure of carbide dispersion strengthened high-entropy alloys

对(CrFeCoNi)高熵合金(HEA)添加5 wt%~20 wt%的WC颗粒进行增强,并通过粉末冶金制备。首先将混合粉末在700 MPa下压实;然后,在真空炉中在1200℃下烧结90 min,研究了烧结样品的密度、相组成和微观结构。估计了硬度、抗压强度、耐磨性和热膨胀系数(CTE)。结果显示添加WC后,合金的密度得到提高。XRD结果表明合金中形成了新的FCC碳化铬相。扫描电子显微镜(SEM)结果显示碳化物相在合金基体上分布良好。通过增加WC含量,CTE逐渐降低。添加WC可以提高抗压强度。建立了数学模型以预测HEA样品的强度行为。随着WC含量的增加,合金的硬度提高约20.35%,此外,无WC HEA的磨损率为1.70×10^(-4) mm^(3)/(N·m),大约是添加20 wt%WC HEA磨损率(3.81×10^(-5) mm^(3)/(N·m))的4.5倍,这意味着合金的耐磨性随WC含量的增加而得到显着改善。

(CrFeCoNi)high-entropy alloy(HEA)was reinforced with various contents of WC particles from 5 wt%to 20 wt%,and prepared by powder metallurgy.The mixed powders were compacted under 700 MPa and then sintered at 1200℃in a vacuum furnace for 90 min.Density,phase composition,and microstructure of sintered samples were investigated.Hardness,compressive strength,wear resistance and coefficient of thermal expansion(CTE)were estimated.The results revealed the improvement of the density with the addition of WC.XRD results revealed the formation of new FCC chromium carbide phases.Scanning electron microscopy(SEM)results show a good distribution of the carbide phases over the alloy matrix.The CTE was decreased gradually by increasing the WC content.Compressive strength was improved by WC addition.A mathematical model was established to predict the behavior of the strength of the HEA samples.The hardness of the investigated HEAs was increased gradually with the increasing of WC content about 20.35%.Also,the wear rate of HEA without WC is 1.70×10^(−4)mm^(3)/(N·m),which is approximately 4.5 times the wear rate of 20 wt%WC HEA(3.81×10^(−5)mm^(3)/(N·m)),which means that wear resistance was significantly improved with the increase of WC content.