摘要
采用真空电弧熔炼制备Nb-16Si-xTi-yZr-zHf (x=18, 22;y=0, 4;z=0, 4;摩尔分数,%)合金并研究Ti、Zr与Hf元素对Nb-Si合金物相组成、显微组织、断裂韧性以及裂纹扩展行为的影响。结果表明:单独添加4%Zr元素能促进(Nb,X)3Si向Nb固溶体(Nbss)/γ-(Nb,X)5Si3共析反应的发生;同时添加Ti、Zr、Hf元素能进一步促进共析反应的发生。裂纹倾向于在(Nb,X)3Si中扩展,当裂纹途径Nb固溶体时会发生偏转。细密的Nbss/γ-(Nb,X)5Si3共晶组织以及层状Nbss/γ-(Nb,X)5Si3共晶组织可以使裂纹产生桥接与分支,阻碍裂纹的扩展。Nb-16Si-22Ti-4Zr-4Hf的合金化元素含量最高,因此,其室温断裂韧性最好(11.62 MPa·m1/2),相较于Nb-16Si-18Ti提高87.7%,性能的提升主要归因于存在层状共晶组织。
The Nb−16Si−xTi−yZr−zHf(x=18,22;y=0,4;z=0,4;at.%)alloys were prepared by arc melting to investigate the influence of elements Ti,Zr and Hf additions on the phase constitution,microstructure,fracture toughness and crack propagation behavior.The results show that the single addition of 4 at.%Zr promotes the eutectoid reaction of(Nb,X)3Si phase to Nb solid solution(Nbss)/γ-(Nb,X)5Si3 eutectic,and simultaneous addition of Ti,Zr and Hf further promotes the eutectoid reaction.The crack trends to propagate in(Nb,X)3Si phase,and the crack deflects when the crack meets Nbss.The fine Nbss/γ-(Nb,X)5Si3 eutectic and Nbss/γ-(Nb,X)5Si3 lamellar structures can induce the crack bridging and branching,and hinder the crack growth.Nb−16Si−22Ti−4Zr−4Hf alloy with the highest content of alloying elements exhibits the highest room-temperature fracture toughness(11.62 MPa·m1/2),which is 87.7%higher than that of the Nb−16Si−18Ti alloy.The performance improvement is mainly attributed to the presence of lamellar eutectic structure.
作者
王琪
赵天宇
陈瑞润
王晓伟
徐琴
王墅
傅恒志
Qi WANG;Tian-yu ZHAO;Rui-run CHEN;Xiao-wei WANG;Qin XU;Shu WANG;Heng-zhi FU(National Key Laboratory for Precision Hot Processing of Metals,School of Materials Science and Engineering,Harbin Institute of Technology,Harbin 150001,China;School of Mechanic and Electrical Engineering,Henan University of Technology,Zhengzhou 450001,China)
基金
support from the National Natural Science Foundation of China (No. 51825401)
the Foundation of National Key Laboratory for Precision Hot Processing of Metals, China (No. JCKYS2021603C001)
the Natural Science Foundation of Heilongjiang Province, China (No. LH2020E032)。
