Development of aluminum alloys with composite structure by squeeze casting process

高强度铝合金/SiC晶须复合材料的特性与质量对挤压铸造工艺制备的Al-Li系合金材料和Al-Li合金/SiC晶须复合材料进行了组织评价，并对每种材料的析出行为进行了研究。AI-2.3wt%Li-0.2wt%Zr和AI-2.3wt%Li-2.8wt%Cu-0.2wt%Zr合金材料在50 ioompa高压下凝固后，凝固组织良好，无孔洞缺陷，固溶热处理后无起泡缺陷，力学性能均较好标本。在100MPa压力下挤压铸造的AI-4wt%Cu-0.7wt%Mg、AI-5wt%Zn-2wt%Mg-1.4wt%Cu、AI-2.3wt%Li和AI-2.3wt%Li -2.8 wt%Cu合金/SiC晶须复合材料的SiC晶须与合金基体之间的界面非常良好，无空穴缺陷。在此复合材料中，淬火态硬度值很高，时效低于200℃时发生时效硬化，随着SiC晶须体积分数的增加，硬度值升高，但时效硬化量减小。在超过200℃的热处理条件下，淬火复合材料即使在过时效状态下也能保持较高的硬化值。在所有复合材料中，碳化硅晶须周围存在许多位错，这是由于碳化硅晶须和合金基体的差异在淬火时引起的。在该区域观察到特殊的老化行为。随着SiC晶须体积分数的增加，沉淀硬化的增量减小。

Characteristics and qualities of high strength aluminum alloys/SiC whisker composites, Al-Li system alloy materials and Al-Li alloy/SiC whisker composites produced by squeeze casting process were estimated structurally and precipitation behaviors in each material were investigated.AI-2.3wt%Li-0.2wt%Zr and AI-2.3wt%Li-2.8wt%Cu-0.2wt%Zr alloy materials solidified under high pressure of 50-IOOMPa have sound solidification structure containing no pore and void defects and have no blister defects after solution heat-treatment and have superior mechanical properties in all of the specimens. AI-4wt%Cu-0.7wt%Mg, AI-5wt%Zn-2wt%Mg-1.4wt%Cu, AI-2.3wt%Li and AI-2.3wt%LI-2.8 wt%Cu alloy/SiC whisker composites processed by squeeze casting with 100MPa pressure have extremely sound interfaces between SiC whiskers and alloy matrices and have no void defects. In these composites, the hardness value at as-quenched state is very high and the age-hardening occurs with aging less than 200ﾟC, and with increase in SiC whisker volume fraction the hardness value raises, but the amount of age- hardening decreases. Under heat-treatment conditions more than 200ﾟC, high harden value of as-quenched composite materials is retained even on over-aging states. In all of these composites, manydislocations exist around SiC whiskers, which were introduced at quenching by the difference in SiC whisker and alloy matrix. In this region, peculiar aging behaviors were observed. Excess vacancies were sunk on interfaces, so precipitation of G.P. zone is retarded and metastable phases precipitates ununiformly, and then the increment in precipitation hardening decreases with increase in volume fraction of SiC whisker.