Thermal stabilizing and toughening of a dual-phase Nb alloy by tuning stabilizing element C in Nb-BCC  

作　　者：Yafang Zhang Xiaojun Zhao Sainan Liu Wei Li Kechao Zhou Lairong Xiao Miao Song Zhenyang Cai 

机构地区：[1]School of Materials Science and Engineering,Central South University,Changsha 410083,China [2]Key Laboratory of Non-ferrous Metal Materials Science and Engineering,Ministry of Education,Central South University,Changsha 410083,China [3]Center for Mineral Materials,School of Minerals Processing and Bioengineering,Central South University,Changsha 410083,China [4]Powder Metallurgy Research Institute,Central South University,Changsha 410083,China

出　　处：《Journal of Materials Science & Technology》2024年第19期207-218,共12页材料科学技术（英文版）

基　　金：supported financially by the National Natural Science Foundation of China(No.51901252);the Hunan Province Natural Science Foundation(No.2023JJ30684);the support from the State Key Laboratory of Powder Metallurgy,Central South University,Changsha,China.

摘　　要：Niobium alloys have found extensive application in industries,such as aerospace,nuclear reactor,and emerging electronic technologies,owing to their high melting point,low density,and remarkable formability.Nevertheless,they still fall short in terms of comprehensive strength,toughness,and thermal stability when subjected to complex impacts and/or torsional forces during service.Here,a dual-phase(BCC/FCC)Nb alloy with attractive mechanical properties and thermal stability was designed by tuning stable element C in the Nb-BCC matrix assisted by hot deformation and aging processes.Our findings reveal that the formation of discontinuous carbides at the grain boundary promotes the phase transformation of the matrix from BCC to FCC(K-S orientation relationship),resulting in the formation of FCC thin layers and nano particles.This unique configuration hinders the slipping of dislocations during deformation and impedes the degeneration of microstructures during the thermal cycling process from 200°C to 900°C.Moreover,the discontinuous carbides at GBs provide channels to transfer dislocations between various phases and/or grains,which results in attractive mechanical properties and thermal stability.The ultimate tensile strength,yield strength,elongation,and elasticity modulus of the designed Nb alloy reach impressive values of 790.5 MPa,436.5 MPa,39.1%,and 63.5 MPa,respectively.These observations provide guidelines for designing dual-phase Nb alloys with remarkable strength,toughness,and thermal stability for aerospace applications by tuning the stabilizing element C in the Nb-BCC matrix.

关 键 词：Strength TOUGHNESS Thermal stability CARBIDE DUAL-PHASE Nb superalloys 

分 类 号：TG14[一般工业技术—材料科学与工程]