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

研究了溶质原子对镁合金高温蠕变特性的影响，通过实验研究了镁合金的高温蠕变行为及其特征，并用最小蠕变速率法比较了镁合金的高温蠕变特性。所研究的合金是镁铝合金，其强化机制预计主要是由尺寸效应引起的固溶强化，以及含有稀土元素的合金。在所有合金中，特别是在含钇的合金中，观察到蠕变中合金化的明显强化效果。固溶体合金中可能存在复合固溶强化效应。镁合金和其他合金无量纲标准化蠕变速率的比较镁基合金和铝基合金中观测到的蠕变速率和报道的蠕变速率基于滑移控制蠕变的物理模型进行标准化。在蠕变激活能与扩散激活能相近的温度下，镁-铝合金的归一化蠕变速率明显低于铝-镁合金，归一化蠕变速率之比在10 ~ 100之间变化。通过改变和控制合金的剪切模量有望成为提高镁合金蠕变强度的一种有效方法。镁合金具有良好的抗蠕变性能，是一种优良的上级轻质耐热材料。

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.