Effect of nano-sized Mo particles on microstructure and mechanical properties of Mo/AZ31 composites

It is a challenge to enhance both strength and ductility for the Mg matrix composites. In the present work, nanostructured Mo-reinforced AZ31 composites are synthesized via powder metallurgy method. The addition of nano-sized Mo particles reduces the grain size and decreases the texture strength of the composites. The Al5Mo and Al8Mo3 phases are formed through Al atoms diffusion and interaction with Mo atoms. The synergistically reinforcing effect of Al5Mo, Al8Mo3 and nano-sized Mo particles improves the mechanical properties of the composites. The nano-Mo/AZ31 composite with 1.0 wt% Mo addition exhibits superior mechanical properties, with yield strength, ultimate tensile strength, and elongation of 221 MPa, 328 MPa and 12.4 %, respectively. These results mean the improvements of 20.1 %, 17.1 % and 21.6 % compared to the AZ31 Mg alloy. The strength enhancement is attributed to the grain refinement and Orowan strengthening, while the improvement in ductility is attributed to grain size reduction, texture weakening, and the activation of a broader range of slip systems.