Extra Strain Hardening in High Pressure Die Casting Mg-Al-RE Alloy

High pressure die casting Mg-Al-RE alloy has an intrinsic and macroscopic gradient structure regarding the grain size and the area fraction of second phase along the depth direction. Such gradient structure exhibits incompatible but continuous mechanical properties in regions of different depth from surface during uniaxial tension. An extra strain hardening and a higher strength are thus produced. The unique mechanical behaviors originate from the generation and accumulation of geometrically necessary dislocations promoted by the strain gradient.