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Abstract: After combined additions of Sr and Sb, most primary Mg2Si crystals in Mg–3.5Si–1Al and Mg–5Si–1Al alloys transformed from equiaxed-dendritic shapes to octahedral morphologies; while eutectic phases also changed from Chinese script to short rod-shapes. The mechanisms of complex modification of Sr and Sb were attributed to the heterogeneous nucleation of primary Mg2Si on Sr11Sb10 nucleus, together with change in growth manners caused by incorporation of Sb in Mg2Si crystals. [Copyright &y& Elsevier]

Abstract: As-cast Mg–3Al–3Sn (AT33) alloy exhibits strong strain hardening ability, which is illustrated by the very high H c and n values. Decrease in generalized stacking fault (GSF) energies in AT33 alloys by Al and Sn additions facilitates the production of dislocations and activation of deformation twins, causing the accumulation of dislocations at twin boundaries, resulting in a high dislocation density in deformed alloys during tension deformation, which thereby mainly accounts for the strong strain hardening ability. [Copyright &y& Elsevier]

Abstract: The wetting and evaporation behaviors of Mg–Al alloys over a full composition range on partially oxidized polycrystalline α-SiC substrates were studied in a flowing Ar atmosphere using an improved sessile drop method. The time dependence of the changes in contact angle and drop geometry was monitored and representative wetting stages were identified. The initial contact angles at 1173K were 100° for pure Al and 76° for pure Mg, with the maximum value of 106° for the 7.6mol.% Mg–Al alloy. The interfacial reaction and the evaporation of Mg led to the decrease in the apparent contact angle in the spreading stage and their respective contribution was evaluated. After the pinning of the triple line, the decrease in the contact angle resulted from the diminishing drop volume as a consequence of the Mg evaporation. The effects of Mg concentration on the wetting and evaporation behaviors were discussed. A mechanism for the time-dependent diminishing drop volume was proposed in light of the competition between the Mg evaporation and its diffusion from the drop bulk to the surface. Finally, the interfacial reaction was analyzed based on thermodynamic considerations. [Copyright &y& Elsevier]