Interphase boundary segregation induced phase transformation in a high-pressure die casting Mg-Al-La-Ca-Mn alloy

Qiang Yang; Shuhui Lv; Pengfei Qin; Fanzhi Meng; Xin Qiu; Xiru Hua; Kai Guan; Wei Sun; Xiaojuan Liu; Jian Meng

Materials & Design (May 2020)

Interphase boundary segregation induced phase transformation in a high-pressure die casting Mg-Al-La-Ca-Mn alloy

Qiang Yang,
Shuhui Lv,
Pengfei Qin,
Fanzhi Meng,
Xin Qiu,
Xiru Hua,
Kai Guan,
Wei Sun,
Xiaojuan Liu,
Jian Meng

Affiliations

Qiang Yang: State Key Laboratory of Rare Earth Resource Utilization, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022, PR China
Shuhui Lv: School of Materials Science and Engineering, Changchun University of Science and Technology, 130022, PR China
Pengfei Qin: State Key Laboratory of Rare Earth Resource Utilization, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022, PR China; Key Laboratory of Superlight Materials & Surface Technology, Ministry of Education, Harbin Engineering University, Harbin 150001, PR China
Fanzhi Meng: School of Materials Science and Engineering, Changchun University of Science and Technology, 130022, PR China; Corresponding authors.
Xin Qiu: State Key Laboratory of Rare Earth Resource Utilization, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022, PR China
Xiru Hua: State Key Laboratory of Rare Earth Resource Utilization, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022, PR China; Key Laboratory of Superlight Materials & Surface Technology, Ministry of Education, Harbin Engineering University, Harbin 150001, PR China
Kai Guan: State Key Laboratory of Rare Earth Resource Utilization, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022, PR China
Wei Sun: State Key Laboratory of Rare Earth Resource Utilization, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022, PR China
Xiaojuan Liu: State Key Laboratory of Rare Earth Resource Utilization, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022, PR China
Jian Meng: State Key Laboratory of Rare Earth Resource Utilization, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022, PR China; Corresponding authors.

Journal volume & issue: Vol. 190

Abstract

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The well-known Al11La3 structure in a die casting Mg-4Al-2La-2Ca-0.3Mn alloy was decomposed when heat treated at 400 °C. Transmission electron microscopy characterizations reveal the decomposition process as: Ca firstly segregated at Mg-Al11La3 interphase, then Al and Ca simultaneously segregated at the interphase boundaries and the radial Al2Ca phase formed, finally the Al11La3 phase gradually decomposed into Al2(Ca,La) structure. First-principles calculations indicate that Ca atoms substituting for La atoms would decrease the stability of Al11La3 and result in that Al11La3 become metastable even at 0 K. Therefore, the decomposition of Al11La3 is attributed to that the interphase boundary segregation of Ca and the diffusion of Ca into Al11La3 change its thermodynamic stability. Keywords: Magnesium alloys, Decomposition, Transmission electron microscopy (TEM), Segregation, Phase stability

Published in Materials & Design

ISSN: 0264-1275 (Print); 1873-4197 (Online)
Publisher: Elsevier
Country of publisher: United Kingdom
LCC subjects: Technology: Electrical engineering. Electronics. Nuclear engineering: Materials of engineering and construction. Mechanics of materials
Website: https://www.journals.elsevier.com/materials-and-design

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