Effect of cooling rate and the original matrix on the thermal diffusion alloyed intermetallic layer on magnesium alloys

In order to promote the utilization of the powder thermal diffusion alloying method to protect magnesium alloys, effect of cooling rate as well as the original state of the magnesium alloy specimens including chemical composition and thickness on the as diffusion alloyed intermetallic layer was investigated. The results show that water quenched specimens could have dendritic crystals in the intermetallic layer even at a diffusion temperature lower than the Mg-Al eutectic temperature. Thinner specimens and higher Al content are preferred for the powder thermal diffusion alloying process. Morphology of the Mg17Al12 intermetallic layer with embedded alpha-Mg islands could be attributed to two main reasons, one is the decomposition of the unstable solution, and the other is liquid saturation and preferential diffusion at heterogeneous structures. (C) 2017 Elsevier Ltd. All rights reserved.