Fabrication and Microstructure Control of High-temperature-resistant Light Alloys Containing Fine Intermetallic Compounds

采用直流铸造和快速凝固技术制备了含过渡元素和稀土元素Zr、Sc、Y、Er、Yb的铝合金。还生产了含银、金、铜、锌的铝锂合金。制备了含Y、Nd、Sm的镁合金。观察了析出组织、变形组织和再结晶组织，并评价了高温下的力学性能。在含Sc合金中，在623K左右形成了具有l1_3型组织的Al_3Sc细晶析出。这些相比Al_3Zr相更能有效地延缓再结晶。快速凝固的Al-Er和Al-Yb合金产生了极细的化合物，有望有效改善合金的性能。Ag、Au和Mg元素的加入提高了Al-Li合金δ相的稳定性。Ag、Au和Mg的加入也大大抑制了δ粒子的粗化速率。含有稀土元素的合金由于亚稳相的析出而表现出明显的时效硬化。高温下的机械强度高于常规镁合金。这可以用含Y、Nd和Sm的镁合金的交叉滑移变形受到抑制来解释。综上所述，含过渡元素和稀土元素的Al和Mg合金在高温下具有良好的组织控制和力学性能。

Aluminum alloys containing transition elements and rare earth elements such as Zr, Sc, Y,Er and Yb were produced using DC-cast and rapid solidification techniques. Al-Li alloys containing Ag, Au, Cu and Zn were also produced. Magnesium alloys containing Y,Nd and Sm were carefully fabricated. Precipitation microstructurs, deformed and recrystallized microstructures were observed and mechanical properties at high temperatures were evaluated.In the alloys containing Sc fine Al_3Sc precipitates with the L1_3-type structure were formed at temperatures around 623K.These precipitates were found to be more effective to retardrecrystallization than Al_3Zr ones. Rapidly solidified Al-Er and Al-Yb alloys produced extremely fine compounds which are expected to be effective to improve alloy properties. The phase stability of the delta'phase in Al-Li alloys was increased with the additional elements of Ag, Au and Mg. The coarsening rate of the delta'particles was also greatly suppressed by the additions of Ag, Au and Mg.Mgalloys containing rare earth elements exhibited markedly increased age-hardening due to the precipitation of the metastable phases. The mechanical strength at high temperatures was higher than that of the conventional Mg alloys. This is explained by the suppressed cross-slip deformation in the Mg alloys containing Y,Nd and Sm.To conclude Al and Mg alloys containing transition elements and rare earth elements produce well controlled microstructures and exhibit improved mechanical properties at high temperatures.