Creep deformation mechanism of magnesium-based alloys |
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Authors: | Jingli Yan Yangshan Sun Feng Xue Jing Bai Shan Xue Weijian Tao |
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Affiliation: | (1) Jiangsu Key Laboratory for Advanced Metallic Materials, Southeast University, Nanjing, 211189, People’s Republic of China;(2) Ford Motor Research & Engineering (Nanjing) Co. Ltd., Nanjing, 211100, People’s Republic of China;(3) Nanjing Welbow Metals Co. Ltd., Honglan, Nanjing, 211221, People’s Republic of China |
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Abstract: | Two heat-resistant magnesium alloys AJC421 and Mg-2Nd were prepared. Both as-cast Mg-2Nd and AJC421 alloys exhibited good
creep resistance in comparison with commonly used magnesium alloys. The improvement in creep properties through Nd addition
to pure magnesium is attributed to both solid solution and precipitation hardening. The stress exponents of 4.5–5.5 and activation
energies of 70.0–96.0 kJ/mol obtained from the as-cast Mg-2Nd alloy at low temperatures and low stresses indicate the five
power law can be used for predicting the creep mechanism. The additions of alkaline earth elements Sr and Ca into Mg–Al alloys
suppress the discontinuous precipitation of Mg17Al12 and form thermal-stable intermediate phases at grain boundaries, leading to effective restriction to grain boundary sliding
and migration. However, the mechanism responsible for creep deformation of Mg–Al based alloys with Ca and Sr additions is
not consistent with the results of microstructure observations performed on the alloys before and after creep tests. |
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