Synergic effect of high temperature and high pressure on consolidation of Mg-4Y-3Nd powder by spark plasma sintering

[Display omitted] •Oxide shells present on powder particles limit diffusion during sintering.•High temperature and high load are beneficial for SPS of Mg-RE alloys.•Rapid diffusion of Y and Nd into powder boundaries causes partial melting.•Oxide shells became unstable and shattered, and interparticle diffusion intensifies. Sintering of magnesium powder is often affected by the oxide layer, which is present on the powder already after gas-atomization. Its negative consequence demonstrates itself usually by limited diffusion between the individual powder particles and formation of compact 3D net-like structures, which promote crack propagation during mechanical loading. This work shows that magnesium-rare earth metals alloys, in this case Mg-4Y-3Nd, can benefit from the utilization of sufficiently high sintering temperature and pressure during the spark plasma sintering. A thorough analysis of the powder boundaries morphology and chemical composition revealed that application of temperature near the eutectic point of Mg-Y/Nd system together with high pressure results in severe diffusion of both Y and Nd into the powder boundaries. Consequently, local change in the chemical composition led to partial melting and the oxide shells became unstable and shattered. As a result, the interparticle diffusion was intensified and the powder consolidation became successful.