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配制和电弧熔炼了MoSi2、(Mo,2at%Nb)Si2、(Mo,6at%Nb)Si2、Mo(Si,2at%Al)2、Mo(Si,4at%Al)2和(Mo,2at%Cr)Si2六种合金,用XRD、SEM-EDS、EPMA、维氏硬度计及压痕法研究了Nb、Al、Cr合金化对MoSi2组织结构、室温硬度及断裂韧性的影响。结果表明,2at%Al、4at%Al和2at%Cr三种合金均得到了单一四方C11b相;6at%Nb合金因Nb含量高,导致部分四方C11b相转变为六方C40相,合金出现灰色C11b基体相与亮白色层片状C40第二相双相组织,部分C40相中存在几乎平行排列的宽度贯穿裂纹。Nb、Al、Cr合金化都降低了MoSi2的维氏硬度,提高断裂韧性,其中2at%Nb、4at%Al合金的断裂韧性最高,达到了5.90MPa.m1/2,提高了69%。
(Mo, 2 at% Nb) Si2, Mo (Si, 2 at% Al) 2, Mo (Si, 4 at% Al) 2 and (Mo, 2 at% Cr) Si2 were investigated by XRD, SEM-EDS, EPMA, Vickers hardness tester and indentation method. The effects of Nb, Al and Cr alloying on microstructure, room temperature hardness and fracture toughness of MoSi2 were studied. The results show that a single tetragonal C11b phase is obtained in 2at% Al, 4at% Al and 2at% Cr alloys. Due to the high content of Nb in 6at% Nb alloy, some tetragonal C11b phases are transformed into hexagonal C40 phases, and the gray C11b matrix Phase and bright white layer C40 second-phase duplex structure, part of the C40 phase exists almost parallel to the width of the through-crack. The alloying of Nb, Al and Cr reduced the Vickers hardness of MoSi2 and improved the fracture toughness. The fracture toughness of 2at% Nb and 4at% Al alloy reached the highest value of 5.90MPa.m1 / 2, which increased 69%.