氧化硅气凝胶对Al-4Cu-0.1Sn合金组织与性能的影响

采用铸造、冷轧和T6热处理制备了SiO₂气凝胶(SA)增强铝基复合材料。研究了SA含量对Al-4Cu-0.1Sn合金显微组织(铸态与冷轧T6态)与力学性能的影响。结果表明,SA能有效地加入到Al-4Cu-0.1Sn合金中,并以球状形式均匀的分布在晶粒内部。铸态下,随着SA含量的增加,合金的显微硬度呈上升趋势。当SA含量为0.02%时,合金平均硬度(HV)达到最高85,相对于未添加SA的合金提升了49%,但铸态下添加SA的合金拉伸性能略微下降;冷轧T6态下,当SA含量为0.02%时,合金硬度(HV)为138。随着SA增加,合金的屈服强度与抗拉强度先升高后降低,当SA含量为0.04%时,合金屈服强度达到320 MPa,抗拉强度达到401MPa,相比于未添加SA的合金提升了10.3%和10.7%。添加SA能够提高铸态Al-4Cu-0.1Sn合金硬度的机理是其细化了铸态合金的晶粒,并使晶界处第二相由粗大的骨骼状变成细小的非连续状。添加SA提高冷轧T6态强度的机理是细化了Al₂Cu相并消除了Al₇Cu₂Fe相。

Effects of Silica Aerogel Content on Microstructure and Mechanical Properties of Al-4Cu-0.1Sn Alloy

SiO₂aerogel(SA)reinforced aluminum matrix composites were prepared by casting,cold rolling and T6heat treatment.The effects of SA content on the microstructure(as-cast and cold-rolled and T6)and mechanical properties of Al-4Cu-0.1Sn alloy were investigated.The results indicate that the SA can be effectively added to the Al-4Cu-0.1Sn alloy,which is uniformly distributed into the crystal grain in form of sphere.In the as-cast state,the microhardness of the alloy shows an upward trend with the increase of SA.When the SA content is 0.02%,the average hardness reaches the highest of HV85,which is 49%higher than that of the alloy without SA,while the tensile properties of the alloy are slightly decreased with SA in the as-cast state.In the cold-rolled T6 state,when the SA content is 0.02%,the hardness of alloy is HV138.With the increase of SA,the yield strength and tensile strength of the alloy are firstly increased and then decreased.When the SA content is 0.04%,the yield strength and tensile strength of the alloy reach 320MPa and 401MPa,respectively,which is 10.3%and 10.7%higher than those of the alloy without SA.The mechanism SA enhancing the as-cast hardness of the Al-4Cu-0.1Sn alloy is to refine grains of the as-cast alloy and lead the second phase at the grain boundary to converting from a coarse skeletal shape to a fine discontinuous shape.The mechanism of adding SA to increase the strength of the T6state is to refine the Al₂Cu phase and eliminate Al₇Cu₂Fe phase.