(1. 陕西科技大学 陕西省无机材料绿色制备与功能化重点实验室，西安 710021；
2. 陕西科技大学 轻工科学与工程学院，西安 710021；
3. 西北工业大学 凝固技术国家重点实验室，西安710072)
摘 要: 采用真空非自耗电弧熔炼法制备了两种系列的Laves相Cr-Nb-Si(Al)合金，利用扫描电镜(SEM)、能谱仪(EDS)、Vickers硬度计及万能力学试验机研究了合金的显微组织、力学性能及强韧化机理。结果表明：随着Al含量不断增加，合金Cr-45Nb-xAl(x=0, 7.5, 17.5)的显微组织由初生相Cr2Nb+共晶Cr2Nb/Nb固溶体(Nbss)演变为全共晶Cr2Nb/Nbss；而随着Si含量不断增加，合金Cr-57.5Nb-xSi(x=0, 5, 10)的显微组织由初生相Nbss+共晶Cr2Nb/Nbss演变为海藻-树枝晶共晶，树枝晶内部为两相共晶Cr2Nb/Nbss，树枝晶边缘为三相共晶Cr2Nb/Nb5Si3/Nbss。合金Cr-45Nb-xAl(x=0, 7.5, 17.5)的压缩强度与断裂韧性随Al含量增加不断减小，而合金Cr-57.5Nb-xSi(x=0, 5, 10)的压缩强度与断裂韧性随Si含量增加呈现先增大后减小的趋势，压缩强度与断裂韧性在Cr-57.5Nb-5Si合金均达到最大值，其值分别为2.5 GPa和15 MPa？m1/2。合金Cr-57.5Nb-5Si优异的强韧性源于析出强化、界面强化、固溶强化、第二相增韧及合金化增韧的协同作用。
关键字: Laves相合金；显微组织；力学性能；强韧化机理
（1. Shaanxi Key Laboratory of Green Preparation and Functionalization for Inorganic Materials, Shaanxi University of Science and Technology, Xi’an 710021, China;
2. College of Bioresources Chemical and Materials Engineering, Shaanxi University of Science and Technology, Xi’an 710021, China;
3. State Key Laboratory of Solidification Processing, Northwestern Polytechnical University, Xi’an 710072, China）
Abstract:Two series of Laves phase alloys Cr-Nb-Si(Al) were prepared by vacuum non-consumable arc melting, and various techniques including SEM, EDS, a Vickers hardness tester, and a universal mechanical testing machine were conducted to study the microstructures, the mechanical properties, and the underling strengthening and toughening mechanisms of these alloys. The results showed that, the microstructures of alloys Cr-45Nb-xAl(x=0, 7.5, 17.5) evolved from primary Cr2Nb plus eutectic Cr2Nb/Nbss to full eutectic Cr2Nb/Nbss with increasing Al content, whereas the microstructures of alloys Cr-57.5Nb-xSi(x=0, 5, 10) transited from primary Nbss plus eutectic Cr2Nb/Nbss to dendritic eutectic. The eutectic within the dendrite was Cr2Nb/Nbss, while transforming to Cr2Nb/Nb5Si3/Nbss at the margin of dendrite. The compression strength and fracture toughness of alloys Cr-45Nb-xAl(x=0, 7.5, 17.5) decreased with increasing Al content, whereas increased firstly and decreased subsequently with increasing Si in the alloys Cr-57.5Nb-xSi(x=0, 5, 10). The compression strength and fracture toughness reached its maximum in the alloy Cr-57.5Nb-5Si and estimated as 2.5 GPa and 15 MPa？m1/2, respectively. The excellent combination of strength and toughness of alloy Cr-57.5Nb-5Si originated from the synergistic effects of precipitation strengthening, interface strengthening, solid solution strengthening, second phase toughening and alloying toughening.
Key words: Laves phase alloys; microstructures; mechanical properties; strengthening and toughening mechanisms
