High Temperature Long-term Strength and Structure Design in High Strength Magnesium Alloys

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Effects of solute atoms on high temperature creep characteristics in magnesiurn alloys.Creep behavior and its characteristics are experimentally investigated in magnesium alloys, and the characteristics are compared by means of minimum creep rates. The examined alloys are magnesium-aluminum alloys whose strengthening mechanism is expected to be solution strengthening mainly caused by size effect, and alloys, which contain rare-earth element. Obvious strengthening effects by alloying in creep are observed in all alloys, especially in alloys, which contain yttrium. Combined solution strengthening effects may operate in solid solution alloys.Comparison of non-dimensional normalized creep rates in magnesium and other alloys.Observed creep rates and reported creep rates in magnesium-based alloys and aluminum-based alloys are normalized based on physical models of glide-controlled creep. The normalized creep rates in magnesium- aluminum alloys are obviously lower than that in aluminum-magnesium alloys, and the ratio in normalized creep rate varies in range 10 to 100, at the temperatures where the activation energies of creep are similar to that for diffusion. Modification and control of share modulus in alloys are expected to be one promising method to improve creep strength in magnesium alloys. Magnesium show good creep resistance and its alloys are considered as superior light heat-resistant materials.Structure control in fully lamellar TiAl alloys and its mechanical properties are experimentally examined.