Decomposition of Nb_(3)Si and mechanical-property improvement by adding appropriate amount of MgO in Nb-16Si-20Ti alloy  

作　　者：De-Zhi Chen Qi Wang Rui-Run Chen Shu Wang Yan-Qing Su Heng-Zhi Fu 

机构地区：[1]National Key Laboratory for Precision Hot Processing of Metals,Harbin Institute of Technology,Harbin,150001,China

出　　处：《Rare Metals》2023年第4期1306-1315,共10页稀有金属（英文版）

基　　金：financially supported by the National Natural Science Foundation of China(Nos.51825401 and 52004077)。

摘　　要：Five Nb-16Si-20Ti-xMgO alloys(x=0,0.1,0.5,1.0 and 3.0)were prepared via arc melting in this study,and the effect of MgO addition on their phase composition,microstructure evolution,and mechanical properties was examined.The results demonstrated that MgO reacted with the Nb-Si-Ti alloy while Mg atoms replaced Nb atoms in the Nbss phase.The hypoeutectic alloy was transformed into a hypereutectic alloy upon the addition of 3.0 at%MgO,and the Nb_(3)Si phases decomposed into a fine Nbss/α-Nb5Si3 eutectic structure.The highest fracture toughness was achieved for the Nb-16Si-20Ti-3MgO alloy,with an ambient fracture toughness value of 9.4 MPa·m^(-1/2)due to its largest Nbss phase content and optimal Nbss/α-Nb_(5)Si_(3)eutectic structure.Furthermore,the alloy compressive strength increased with MgO addition.The compressive strength of the Nb-16Si-20Ti-3MgO alloy was 2624.1 MPa,26.0%higher than that of Nb-16Si-20Ti,due to the formation of a solid solution of Mg atoms in the Nbss phase and reinforcement of a small amount of the Ti_(2)O phase.Finally,an increase in the content of the Nbss/α-Nb_(5)Si_(3)eutectic structure increased both the alloy strength and fracture strain.

关 键 词：Niobium silicon alloy Magnesium oxide Eutectic structure Fracture toughness 

分 类 号：TG132[一般工业技术—材料科学与工程] V252[金属学及工艺—合金] V263[金属学及工艺—金属学]