文献类型：期刊文献

英文题名：High-cycle fatigue induced twinning in CoCrFeNi high-entropy alloy processed by laser powder bed fusion additive manufacturing

作者：Chen, Yinan[1];Li, Bo[1,2];Chen, Bo[3];Xuan, Fuzhen[1,4]

机构：[1]East China Univ Sci & Technol, Sch Mech & Power Engn, Shanghai 200237, Peoples R China;[2]East China Univ Sci & Technol, Addit Mfg & Intelligent Equipment Res Inst, Shanghai 200237, Peoples R China;[3]Univ Leicester, Sch Engn, Leicester LE1 7RH, England;[4]Shanghai Collaborat Innovat Ctr High End Equipment, Shanghai 200237, Peoples R China

年份：2023

卷号：61

外文期刊名：ADDITIVE MANUFACTURING

收录：;EI(收录号：20225013247013);WOS:【SCI-EXPANDED(收录号:WOS:000895563200003)】；

基金：This work is financially sponsored by National Natural Science Foundation of China (Grant No. 52175140), Natural Science Foundation of Shanghai, in China (Grant No. 20ZR1414000), International Collaboration Program from Science and Technology Commission of Shanghai Municipality, China (Grant No. 19110712500). Bo Chen acknowledges financial supports by the UK's Engineering and Physical Sciences Research Council, EPSRC Early Career Fellowship Scheme EP/R043973/1 and East China University of Science and Technology (ECUST) through the Ministry of Education of the People's Republic of China 'the 111 Project'. Bo Chen is very grateful for Prof Shan-Tung Tu at ECUST who has been consistently introducing many opportunities and providing resources to allow Bo Chen to develop new collaborations.

语种：英文

外文关键词：Fatigue; Twinning; Cellular structure; High-entropy alloy; Laser powder bed fusion

摘要：High-cycle fatigue (R=0.1, room temperature) induced microstructural evolution in a laser powder bed fusion (L-PBF) additively manufactured quaternary CoCrFeNi high-entropy alloy (HEA) was studied. The as-built material exhibited a combined < 001 > and < 110 > texture and high proportion of low-angle boundaries. Electron backscatter diffraction (EBSD) and transmission electron microscopy (TEM) revealed that deformation twinning occurred under the high-cycle fatigue of sigma(max )= 450 MPa (N-f=1.06 x10(5)), but not for the stress level o(f )300 MPa and 200 MPa. The deformation twins led to the cyclic softening, as manifested by the continuous increase of maximum strain under the stress-controlled fatigue, and the hardness increased by similar to 80 HV0.2 in the postfatigued condition. EBSD revealed that both the < 001 > and < 110 > orientations were favorable for the twin formation. Given that the size of grains with the < 001 > and < 110 > orientations was twice larger than those of the other orientations, the grain size effect on twin formation could play a certain role. High-resolution TEM revealed that the full dislocations, lattice distortion, stacking faults, and partial dislocations were associated with the twin, cellular and labyrinth wall-like dislocation structures. The underlying mechanism for the formation of nano-twins during high-stress fatigue involved the dissociation of 1/2 < 110 > full dislocations to 1/6 < 112 > partial ones. Moreover, the dislocation cell structure as observed in the as-built condition evolved into sub-grains after the high-cycle fatigue loading, with the immensely dense dislocations at the sub-grain boundary.