On the strength and fracture toughness of an additive manufactured CrCoNi medium-entropy alloy

被引：52

作者：

Kumar, Punit ^{[1
,2
]}

Michalek, Matthew ^{[1
]}

Cook, David H. ^{[1
,2
]}

Sheng, Huang ^{[3
]}

Lau, Kwang B. ^{[4
]}

Wang, Pei ^{[4
]}

Zhang, Mingwei ^{[1
,2
]}

Minor, Andrew M. ^{[1
,2
,5
]}

Ramamurty, Upadrasta ^{[3
,4
]}

Ritchie, Robert O. ^{[1
,2
]}

机构：

[1] Univ Calif Berkeley, Dept Mat Sci & Engn, Berkeley, CA 94720 USA

[2] Lawrence Berkeley Natl Lab, Mat Sci Div, Berkeley, CA USA

[3] Nanyang Technol Univ, Sch Mech & Aerosp Engn, Singapore, Singapore

[4] Agcy Sci, Inst Mat Res & Engn, Technol & Res A STAR, Singapore, Singapore

[5] Lawrence Berkeley Natl Lab, Natl Ctr Electron Microscopy, Mol Foundry, Berkeley, CA USA

来源：

ACTA MATERIALIA | 2023年 / 258卷

基金：

美国国家科学基金会;

关键词：

Medium-entropy alloys; Additive manufacture; Laser powder bed fusion; Mechanical properties; Strengthening; Toughening; STAINLESS-STEELS; CRACK; DEFORMATION; MECHANISMS; BEHAVIOR;

D O I：

10.1016/j.actamat.2023.119249

中图分类号：

T [工业技术];

学科分类号：

08 ;

摘要：

An additively manufactured (nominally equiatomic) CrCoNi alloy was processed by laser powder bed fusion (LPBF). At ambient temperatures (298 K), this medium-entropy alloy displayed a yield strength, ay of-691 & PLUSMN; 9 MPa, and an ultimate tensile strength, au of-926 & PLUSMN; 15.2 MPa; at cryogenic temperatures (77 K), yield and tensile strengths increased respectively to ay -944 & PLUSMN; 6 MPa and au -1382 & PLUSMN; 11 MPa. These strength levels are 57 and 44% higher than that of the wrought alloy, due to strengthening from the solidification cellular structures intertwined with dislocations in the LPBF CrCoNi. The crack-initiation fracture toughness, KJIc was measured to be-183.7 & PLUSMN; 28 MPa & RADIC;m at 298 K; this value marginally decreased by-4% to-176 & PLUSMN; 11 MPa & RADIC;m at 77 K. These KJIc values of the LPBF CrCoNi were 11% and 35% lower than the wrought CrCoNi alloy at 298 K and 77 K, respectively. The resistance to crack growth of the LPBF CrCoNi from its hierarchical micro-and meso-structures was evaluated using nonlinear-elastic fracture mechanics by measuring R-curve behavior in the form of the J -integral as a function of crack extension. The specific features of the hierarchical microstructures at different length-scales provide a basis for the strengthening and toughening properties of this additively manufactured medium-entropy alloy. This correlation between the deformation and the hierarchical microstructures at different length-scales may provide future guidance for improving the fracture toughness properties of medium -entropy alloys.

引用

页数：12

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