Strengthening and Toughening Behaviors of the Mg-9AI Alloy Containing Oxygen Atoms

摘要

New Mg-0-9Al alloy has been developed by the dispersion of oxygen atoms in the Mg-9A1 alloy in which oxygen atoms are supplied from the decomposition of Ti0_2 nanoparticles in the Mg-9A1 alloy melt. The dissolved oxygen atoms expand the lattice structures of both oc-Mg and P-phase, inducing the reduced mismatch distance between α-Mg and β-phase. Therefore, yield stress of the Mg-O-9Al alloy is 143 MPa. much higher than 110 MPa in the Mg-9A1 alloy. Fracture toughness values of 10.39 MPa m~(1/2) and 12.86 MPa m~(1/2) for both the Mg-9A1 and Mg-0-9Al alloys are also respectively obtained. The crack propagates along the weak interface of β-phase in the Mg-9A1 alloy. On the other hand, the P-phase disturbs the crack propagation route in the Mg-O-9A1 alloy, showing many broken P-phases. Therefore, the improved interfacial feature with an addition of dissolved oxygen atoms in the Mg-0-9Al alloy results in much enhanced mechanical properties.