Abstract
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 forma-bility.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 trans-formation 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 ℃ to 900 ℃.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 sta-bility.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 obser-vations 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.
基金项目
National Natural Science Foundation of China(51901252)
Hunan Province Natural Science Foundation(2023JJ30684)
NETL
NSTL
万方数据