FeCoNiTi_(x)中熵合金组织性能及其在硬质合金中的应用

Microstructure and Properties of FeCoNiTi_(x) Medium-Entropy Alloy and Its Application in Cemented Carbides

FeCoNi中熵合金相比传统合金具有优异的性能,但其室温强度不高,限制了其应用。通过机械合金化和放电等离子烧结工艺制备FeCoNiTi_(x)(x=0,0.25,0.50,0.75,1)中熵合金块体,重点研究了各元素机械合金化顺序以及Ti含量对FeCoNiTi_(x)中熵合金显微组织和性能的影响,并初步探讨了FeCoNiTi_(x)中熵合金作为黏结剂在WC基硬质合金中的应用。结果表明:机械合金化过程中FeCoNi基体相为FCC相,添加Ti元素后形成Laves相和钛氧化物相,因此FeCoNiTi_(x)中熵合金物相由FCC相、Laves相和钛氧化物相组成。随着Ti含量的增加,FeCoNiTi_(x)合金密度、硬度和强度均上升,塑性先增强后减弱。FeCoNiTi_(0.50)中熵合金表现出良好的力学性能,其显微硬度、屈服强度、压缩强度和压缩应变分别为531 HV、1 987.57 GPa、2 114.85 GPa和20.5%。添加少量Ti元素可提升FeCoNi合金的耐腐蚀性。FeCoNiTi_(x)黏结剂在WC基硬质合金中能稳定存在,抑制WC烧结过程中脱碳相的形成。WC-FeCoNiTi_(0.50)硬质合金表现出较好的力学性能,其显微硬度与断裂韧性分别为1 834 HV与15.12 MPa·m^(1/2)。

FeCoNi medium-entropy alloy exhibits excellent properties compared with traditional alloys,but its room temperature strength is not high,which limits its application.The blocks of FeCoNiTi_(x)(x=0,0.25,0.50,0.75,1)medium-entropy alloy were prepared by mechanical alloying and spark plasma sintering.The effects of mechanical alloying sequence of each element and Ti content on the microstructure and properties of FeCoNiTi_(x) medium-entropy alloy were emphasized.Additionally,preliminary exploration was conducted on the application of FeCoNiTi_(x) medium-entropy alloy as binder in WC-based cemented carbides.The results show that the FeCoNi matrix phase is FCC phase during mechanical alloying,and the addition of Ti element results in the formation of Laves phase and titanium oxide phase.Therefore,the phase of FeCoNiTi_(x) medium-entropy alloy consists of FCC phase,Laves phase and titanium oxide phase.With the increase of Ti content,the density,hardness and strength of FeCoNiTi_(x) alloy increase,while the plasticity increases at first and then decreases.The FeCoNiTi_(0.50)medium-entropy alloy exhibits good mechanical properties,and its microhardness,yield strength,compressive strength and compressive strain are 531 HV,1987.57 GPa,2114.85 GPa and 20.5%,respectively.The addition of a small amount of Ti element can enhance the corrosion resistance of FeCoNi alloy.FeCoNiTi_(x) binder can exist stably in WC-based cemented carbides,inhibiting the formation of decarburization phase in the sintering process of WC.WC-FeCoNiTi_(0.50)cemented carbide exhibits good mechanical properties,and its microhardness and fracture toughness are 1834 HV and 15.12 MPa·m^(1/2),respectively.