Utilization of VN particles for grain refinement and mechanical properties of AZ31 magnesium alloy

The influence of VN particles on the grain refinement and mechanical properties of AZ31 magnesium alloy was investigated and the refining and reinforcing mechanisms were also discussed. These particles present remarkable grain refining efficiency on AZ31 alloy. Addition of 0.5 wt% VN into AZ31 alloy led to decreasing the average grain size from 115.7 μm to 62.4 μm. X-Ray Diffraction and energy dispersive spectroscopy showed the existence of AlN, which was in situ produced through the reaction of VN and Al. Based on the phase identification and disregistry calculation, it was confirmed that the refinement of AZ31 alloy was mainly ascribed to duplex phase composed of AlN and VN acting as nucleating substrates of α-Mg during solidification. Improved mechanical properties were achieved after addition of VN. Yield strength (YS) increased from 39.5 MPa to 50.3 MPa with addition of 1 wt% VN. 0.5 wt% VN into AZ31 alloy exhibited the best mechanical properties with a YS of 47.1 MPa, an ultimate tensile strength (UTS) of 197.4 MPa and an elongation (EI) of 17.8%, enhancing the AZ31 alloy by about 19.2%, 40.3% and 67.9%, respectively.