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Additive Manufacturing of High Strength Copper Alloy With Heterogeneous Grain Structure Through Laser Powder Bed Fusion

39 Pages Posted: 29 Apr 2021 Publication Status: Under Review

See all articles by Yingang Liu

Yingang Liu

University of Queensland - School of Mechanical and Mining Engineering

Jingqi Zhang

University of Queensland - School of Mechanical and Mining Engineering

Qiyang Tan

University of Queensland - School of Mechanical and Mining Engineering

Yu Yin

University of Queensland - School of Mechanical and Mining Engineering

Shiyang Liu

University of Queensland - School of Mechanical and Mining Engineering

Meng Li

University of Queensland - School of Mechanical and Mining Engineering

Miaoquan Li

Northwestern Polytechnical University - School of Materials Science and Engineering

Qiong Liu

Queensland University of Technology - School of Mechanical, Medical and Process Engineering

Ying Zhou

Queensland University of Technology - School of Mechanical, Medical and Process Engineering

Tao Wu

HBIS Group

Feng Wang

HBIS Group

Ming-Xing Zhang

University of Queensland - School of Mechanical and Mining Engineering

Abstract

The low laser processability of pure copper (Cu) commonly causes high porosity, and therefore low strength of additively manufactured (AMed) Cu parts. The current work reports an effective approach to solve this problem through inoculation of pure Cu powder with cobalt (Co) submicron particles. Co addition enabled increase in laser absorptivity, and therefore dense Cu was fabricated through laser powder bed fusion even though typical AM featured coarse columnar grains were produced when Co addition was 4 wt.% or less. Significant grain refinement with heterogeneous grain structure (HGS) was achieved when the addition level was greater than the maximum solid solubility of Co in Cu (4.75 wt.%), such as 6 and 8 wt.%. HGS is characterized with ultrafine equiaxed grains close to melt pool boundaries and coarser equiaxed grains or columnar grains near centres of melt pools. Heterogenous nucleation of Cu near melt pool boundaries, where were associated with larger thermal undercooling due to faster cooling rate, was responsible for the formation of ultrafine equiaxed grains. In contrast, heterogeneous nucleation near centres of melt pools was suppressed. Detailed substructure examination indicated that heterogenous nucleation occurred on dual phase nanoparticles containing Co shell and cobalt oxide (CoO) core. The higher affinity of Co to oxygen caused formation of CoO. HGS of Cu significantly improved both strength and ductility. After direct ageing at 600°C for one hour, a tensile strength of 491.1±12.6 MPa, elongation of 27.3±2.5% and electrical conductivity of 61.5% IACS (International Annealed Copper Standard) were achieved.

Keywords: Copper alloys; additive manufacturing; grain refinement; heterogeneous nucleation of phase; age hardening

Suggested Citation

Liu, Yingang and Zhang, Jingqi and Tan, Qiyang and Yin, Yu and Liu, Shiyang and Li, Meng and Li, Miaoquan and Liu, Qiong and Zhou, Ying and Wu, Tao and Wang, Feng and Zhang, Ming-Xing, Additive Manufacturing of High Strength Copper Alloy With Heterogeneous Grain Structure Through Laser Powder Bed Fusion. Available at SSRN: https://ssrn.com/abstract=3836798 or http://dx.doi.org/10.2139/ssrn.3836798

Yingang Liu

University of Queensland - School of Mechanical and Mining Engineering ( email )

St Lucia
Brisbane, Queensland 4072
Australia

Jingqi Zhang

University of Queensland - School of Mechanical and Mining Engineering ( email )

St Lucia
Brisbane, Queensland 4072
Australia

Qiyang Tan

University of Queensland - School of Mechanical and Mining Engineering

St Lucia
Brisbane, Queensland 4072
Australia

Yu Yin

University of Queensland - School of Mechanical and Mining Engineering

St Lucia
Brisbane, Queensland 4072
Australia

Shiyang Liu

University of Queensland - School of Mechanical and Mining Engineering

St Lucia
Brisbane, Queensland 4072
Australia

Meng Li

University of Queensland - School of Mechanical and Mining Engineering

St Lucia
Brisbane, Queensland 4072
Australia

Miaoquan Li

Northwestern Polytechnical University - School of Materials Science and Engineering ( email )

127 YouYi Load
XiAn, Shaanxi 710072
China

Qiong Liu

Queensland University of Technology - School of Mechanical, Medical and Process Engineering

Brisbane
Australia

Ying Zhou

Queensland University of Technology - School of Mechanical, Medical and Process Engineering

Brisbane
Australia

Tao Wu

HBIS Group

China

Feng Wang

HBIS Group

China

Ming-Xing Zhang (Contact Author)

University of Queensland - School of Mechanical and Mining Engineering ( email )

St Lucia
Brisbane, Queensland 4072
Australia

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