Exploring the correlation between solvent diffusion and creep resistance of Mg-Ga HCP alloys from high throughput liquid-solid diffusion couple

Abstract

The liquid-solid diffusion couple technique, supported by phenomenological analysis and nano-indentation tests, is proposed on account of the relatively low melting points of Mg to explore the diffusion mobility and creep deformation. The potential of this strategy is demonstrated in MgGa hcp alloys where Ga solute (i.e. impurity) and Mg solvent diffusions in hcp MgGa alloys were both unveiled. It was followed by mapping the compressive creep behavior via nanoindentation along the composition arrays within the same MgGa couple sample. The compressive creep resistance of MgGa hcp alloys increased with the Ga content, and this enhancement was similar to the one found in MgZn alloys and superior to the one reported in MgAl alloys though Al is a slower impurity diffuser in hcp-Mg than Zn and Ga. Thereby, the solvent diffusion and its variation with the composition, rather than the solute diffusion, was suggested to govern the creep properties at high temperatures and low stresses.