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Title: Hardness and microstructural inhomogeneity at the epitaxial interface of laser 3D-printed Ni-based superalloy

Here in this letter, microstructural and mechanical inhomogeneities, a great concern for single crystal Ni-based superalloys repaired by laser assisted 3D printing, have been probed near the epitaxial interface. Nanoindentation tests show the hardness to be uniformly lower in the bulk of the substrate and constantly higher in the epitaxial cladding layer. A gradient of hardness through the heat affected zone is also observed, resulting from an increase in dislocation density, as indicated by the broadening of the synchrotron X-ray Laue microdiffraction reflections. Lastly, the hardening mechanism of the claddin g region, on the other hand, is shown to originate not only from high dislocation density but also and more importantly from the fine γ/γ' microstructure.
Authors:
 [1] ;  [2] ;  [1] ; ORCiD logo [1] ; ORCiD logo [1] ;  [2] ; ORCiD logo [3] ;  [4] ;  [1] ;  [1]
  1. Xi'an Jiaotong Univ., Shaanxi (China). State Key Lab. for Mechanical Behavior of Materials
  2. Xi'an Jiaotong Univ., Shaanxi (China). State Key Lab. for Manufacturing Systems Engineering
  3. Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Advanced Light Source (ALS)
  4. Xi'an Jiaotong Univ., Shaanxi (China). State Key Lab. for Manufacturing Systems Engineering
Publication Date:
OSTI Identifier:
1377476
Grant/Contract Number:
AC02-05CH11231; 51671154; 51302207; 51275392; 11132006; 2016YFB0700404; 2015CB057400; 2015gjhz03
Type:
Accepted Manuscript
Journal Name:
Applied Physics Letters
Additional Journal Information:
Journal Volume: 109; Journal Issue: 10; Journal ID: ISSN 0003-6951
Publisher:
American Institute of Physics (AIP)
Research Org:
Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; Hardness; Cladding; Epitaxy; Dislocations; Nanopowders