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In this work, fracture toughness and flexural properties including flexural modulus, flexural stresshtrain of 2 molding compounds GMC-1 and GMC-2 were investigated in a temperature range from -6OOC to 260°C, whereby three-point-bending method was applied to all tests. To observe the moisture effect on those mechanical properties, specimens were soaked under 85OC/85%RH conditions for 168 hours following the moisture reflow standards (for moisture tests) or baked for at least 24 hours (for dry tests) before tests. The obtained results are then compared with each other.It is seen that at high temperature, rupture stress of the 2 MCs at 85'C/85% RJ3 condition could be 40%-50% lower than those at dry conditions. The remarkable reduction of material strength will largely promote the failure in the packages considering that modulus change does not change significantly the stress level. It is also found that using the material data for GMC-1 provided by vendor could underestimate maximum Von Mises stress by around 15% at high temperature.Similarly, fracture toughness decreases greatly with temperature and moisture content. At 260°C, maximum Von Mises stress could be reduced by 40% due to the moisture take-up change from dry to wet (MSL1).

Magnesium alloys on the surface of billets might be refined by chilled casting process, but the grains of the center of billets are coarse, and there are a lot of void defects in the center of billets. These defects can be eliminated by hot extrusion, while fibrous microstructures and strong basal textures might be formed. This paper presents a new short process technology which includes chilled casting and extrusion-shear (CCES). It is crucial to understand the effects of die structures on the deformation behaviors, strain distribution and load requirements. Three selections of processes and die structures were done by simulations and experiments which include CCES process with 4 times consecutive shearings plastic deformation, CCES process by lateral extrusion with 90° shearing angle, and combined CCES process mode. The research results show the third selection is recommended. Three-dimensional (3D) geometric models with different channel angles (30°, 45°) for the third selection CCES dies were designed. The heterogeneities of plastic deformation by CCES dies with different channel angles were analyzed from the simulation results. The simulation results show strains decrease with rising of channel angles. The lower channel angles improve the deformation heterogeneity of magnesium alloy billets. Smaller channel angles obtain higher strains and produce tinier sub-grains. The forces of the CCES process decrease with rising of channel angles. The analysis results showed that finer and uniform microstructures can be obtained if channel angles in the CCES dies are appropriate.

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