ISSN: 1003-6326
CN: 43-1239/TG
CODEN: TNMCEW

Vol. 30    No. 4    April 2020

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Microstructural evolution and creep properties of Mg-4Sn alloys by addition of calcium up to 4 wt.%
Amir BAGHANI1, Hamid KHALILPOUR2, Seyed Mahdi MIRESMAEILI3
(1. Department of Mechanical Engineering, University of Iowa, Iowa City, IA, USA;
2. Department of Mining, Metallurgical and Materials Engineering, Laval University, Québec, Canada;
3. Faculty of Mechanical Engineering, Shahid Rajaee Teacher Training University, Tehran, Iran
)
Abstract: The effects of addition of calcium up to 4 wt.% on the microstructure and creep properties of Mg-4Sn alloys were investigated by the impression creep test. Impression creep tests were performed in temperature range between 445 and 475 K under normalized stresses σ/G (where σ is the stress; G is the shear modulus) between 0.0225 and 0.035. Optical microscopy and scanning electron microscopy were used to study the microstructure of samples. It is observed that the addition of Ca more than 2 wt.% suppresses less stable MgSn2 phase, and instead forms more thermally stable phases of Ca-Mg-Sn and Mg2Ca at the grain boundaries which improve the creep resistance of Mg-4Sn alloys. According to the stress exponents (6.04<n<6.89) and activation energies (101.37 kJ/mol<Q<113.8 kJ/mol) which were obtained from the impression creep tests, it is concluded that the pipe diffusion climb controlled dislocation creep is the dominant creep mechanism.
Key words: impression creep test; Mg-Sn-Ca alloy; creep mechanism; microstructure
Superintended by The China Association for Science and Technology (CAST)
Sponsored by The Nonferrous Metals Society of China (NFSOC)
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