Fe/Ni比对WC-Fe-Ni硬质合金微观组织及性能的影响

Effects of Fe/Ni ratio on microstructure and properties of WC-Fe-Ni cemented carbide

在1450℃下低压烧结制备5种不同Fe/Ni比(质量比)的WC-Fe-Ni硬质合金,通过SEM、TEM、XRD、力学性能测试和电化学测试研究Fe/Ni比对硬质合金的显微组织和性能的影响。结果表明:随Fe/Ni比增大,晶粒尺寸先下降后上升;Fe/Ni比为3:1时,合金晶粒尺寸最小,为1.24μm;合金抗弯强度变化趋势和晶粒尺寸变化呈反比;硬度不断提高,断裂韧性变化与烧结致密度变化均保持先上升后下降趋势;在Fe/Ni比为3:1时,合金断裂方式主要为沿晶断裂,在Fe/Ni比不等于3:1时会出现较多穿晶断裂;合金耐酸性溶液腐蚀能力不断变差。当Fe/Ni比为3:1时,合金的综合性能最好,其硬度、抗弯强度、断裂韧性、腐蚀电流密度分别达到934HV、3047MPa、23.3 MPa?m^(1/2)、3.98×10^(-5) A/cm^2。

WC-Fe-Ni cemented carbides with five kinds of Fe/Ni ratio were prepared by 1450℃sinter-HIP sintering to study the effects of Fe/Ni ratio on the microstructure and properties by SEM,XRD,mechanical performance test and electrochemical test.The results show that with the increase of Fe/Ni ratio,the grain size firstly decreases and then increases.The grain size reaches the finest(1.24μm)with Fe/Ni ratio of 3:1.And with the increase of Fe/Ni ratio,the changing trend between bending strength and grain size is inverse,the hardness increases continuously,both of fracture toughness and sintering density firstly increase and then decrease.When Fe/Ni ratio is 3:1,fracture mode is mainly intergranular fracture.Except for the alloy with Fe/Ni ratio of 3:1,more transgranular fracture appears.The acidic corrosion resistance ability gets worse continuously.When Fe/Ni ratio is 3:1,WC-Fe-Ni alloy exhibits optimum properties,the hardness,bending strength,fracture toughness and corrosion current density are 3047 MPa,934HV,23.3 MPa-m1/2 and 3.98×10^-5 A/cm^2,respectively.