Formation mechanism of growth twins in Mg–3Gd–0.6Zr alloy

ABSTRACT

A cast Mg–3Gd–0.6Zr alloy with microscale $\left\{10\overline{1}2\right\}$ growth twins was designed successfully. After the alloy was annealed at 350°C for 1 h, the volume fraction of the growth twins was increased by approximately 120%. Gd solute atoms segregated on both sides of twin boundaries and facilitated their formation in the as–cast alloy. The formation mechanism of $\left\{10\overline{1}2\right\}$ growth twins in the as–cast alloy was discussed in five aspects: the supersaturation of Gd solute atoms, the segregation ability of Gd, the composition of Gd, the nucleate sites of growth twins, and the total energy of the system. The growth twins elicited remarkable toughening effect but a moderate strengthening effect on the alloy.

KEYWORDS:

• Magnesium alloys
• growth twins
• formation mechanism
• mechanical properties
• casting

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This work was supported by the National Key Research and Development Program of China [grant number 2016YFB0301100]; Chongqing Research Program of Basic Research and Frontier Technology [grant numbers CSTC2017JCYJBX0051 and CSTC2018JCYJAX0472]; Science and Technology Rese-arch Program of Chongqing Municipal Education Commission [grant numbers KJQN201801312, KJQN201801306, and KJQN201801314] and Talent projects of Chongqing University of Arts and Sciences [grant numbers 2017RXC24, R2014CJ04, and P2017XC08].