Uncovering the Role of Solute in Grain Refinement of Additively Manufactured Aluminium Alloys

38 Pages Posted: 17 Jun 2021

See all articles by Qiyang Tan

Qiyang Tan

University of Queensland - School of Mechanical and Mining Engineering

Yu Yin

University of Queensland

Feng Wang

HBIS Group Technology Research Institute

Shiyang Liu

University of Queensland

Arvind Prasad

University of Queensland

Wenying Qu

Southern University of Science and Technology - Shenzhen Key Laboratory for Additive Manufacturing of High-Performance Materials

Gan Li

Southern University of Science and Technology

Tao Wu

HBIS Group Technology Research Institute

Jingqi Zhang

University of Queensland - School of Mechanical and Mining Engineering

Yingang Liu

University of Queensland - School of Mechanical and Mining Engineering

Xianliang Yang

HBIS Group

Qiang Zhu

Southern University of Science and Technology - Shenzhen Key Laboratory for Additive Manufacturing of High-Performance Materials

David Henry St. John

University of Queensland - School of Mechanical and Mining Engineering

Ming-Xing Zhang

University of Queensland - School of Mechanical and Mining Engineering

Abstract

Grain refinement is one of the most effective approaches to improving mechanical properties, reducing anisotropy and hot-cracking of additively manufactured alloys. Recent studies have shown that the extreme solidification conditions associated with additive manufacturing (AM), including large thermal gradient and rapid cooling rate, result in the difference in nucleation and grain growth mechanisms between AM and conventional casting. Thus, it is necessary to re-consider the grain refinement mechanisms, particularly the role of solute during AM. The present work investigates the grain refining efficiencies of different solute additives (Si, Cu and Ni) and their integration with nucleants (LaB6 nanoparticles) in additively manufactured pure Al. It was found that, despite the rapid cooling during AM and nucleant inoculation, solute addition is essential for activating heterogeneous nucleation upon solidification to achieve high grain refining efficiency. However, the role of solute in grain refinement during AM cannot be readily interpreted by the classic grain growth restriction theory (Q value). This is attributed to the large thermal gradient in the melt pools during AM solidification, which significantly limits the development of constitutional supercooling. Alternatively, the role of solute can be better understood in terms of the lag in dendrite growth induced by solute rejection during solidification. This causes the difference between the actual dendrite growth and the theoretical pull rate, generating large thermal undercooling at the solidification front to elicit heterogeneous nucleation. This work sheds new light on the factors affecting grain refinement under rapid solidification.

Keywords: Selective laser melting; Aluminum alloys; Grain refinement; EBSD; SEM

Suggested Citation

Tan, Qiyang and Yin, Yu and Wang, Feng and Liu, Shiyang and Prasad, Arvind and Qu, Wenying and Li, Gan and Wu, Tao and Zhang, Jingqi and Liu, Yingang and Yang, Xianliang and Zhu, Qiang and St. John, David Henry and Zhang, Ming-Xing, Uncovering the Role of Solute in Grain Refinement of Additively Manufactured Aluminium Alloys. Available at SSRN: https://ssrn.com/abstract=3869172 or http://dx.doi.org/10.2139/ssrn.3869172

Qiyang Tan (Contact Author)

University of Queensland - School of Mechanical and Mining Engineering

St Lucia
Brisbane, Queensland 4072
Australia

Yu Yin

University of Queensland

St Lucia
Brisbane, 4072
Australia

Feng Wang

HBIS Group Technology Research Institute ( email )

China

Shiyang Liu

University of Queensland

St Lucia
Brisbane, 4072
Australia

Arvind Prasad

University of Queensland

St Lucia
Brisbane, 4072
Australia

Wenying Qu

Southern University of Science and Technology - Shenzhen Key Laboratory for Additive Manufacturing of High-Performance Materials ( email )

No 1088, xueyuan Rd.
Xili, Nanshan District
Shenzhen, Guangdong 518055
China

Gan Li

Southern University of Science and Technology

No 1088, xueyuan Rd.
Xili, Nanshan District
Shenzhen, 518055
China

Tao Wu

HBIS Group Technology Research Institute ( email )

China

Jingqi Zhang

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

St Lucia
Brisbane, Queensland 4072
Australia

Yingang Liu

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

St Lucia
Brisbane, Queensland 4072
Australia

Xianliang Yang

HBIS Group ( email )

China

Qiang Zhu

Southern University of Science and Technology - Shenzhen Key Laboratory for Additive Manufacturing of High-Performance Materials ( email )

No 1088, xueyuan Rd.
Xili, Nanshan District
Shenzhen, Guangdong 518055
China

David Henry St. John

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

St Lucia
Brisbane, Queensland 4072
Australia

Ming-Xing Zhang

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

St Lucia
Brisbane, Queensland 4072
Australia

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