温度及溶质浓度对Mullite短纤维增强的Al-Cu复合材料及其基体合金时效行为的影响

Effects of Temperature and Solute Content on the Ageing Behaviour of the Al-Cu Composite Reinforced by Short Mullite Fibers and Its Base Alloy

用挤压铸造方法制备Mullite/Al-Cu复合材料及其基体合金。用硬度测试(HB)、差示扫描量热仪(DSC)和透射电镜(TEM)等手段,研究了温度和溶质原子浓度对复合材料及其基体合金时效行为的影响。结果表明:复合材料和基体合金具有相似的时效硬化曲线及相同的时效析出序列,随时效温度的升高,峰值硬度降低、析出过程加快;溶质浓度升高,峰值硬度升高、析出过程同样得到加快;纤维除了能明显提高Al-Cu合金的时效硬度外,还能加速其时效析出过程,但对GP区的形成具有明显的抑制作用,而对θ相的析出影响不大。

Short mullite fibre reinforced Al-Cu composites and their base alloys were produced by squeeze casting method. The effects of temperature and solute content (3.5Cu, 4.0Cu and 4.5Cu) on the ageing behaviour of the composites and the monolithic alloys have been studied by means of hardness measurement (HB), differential scanning calorimetry(DSC) and transmission electron microscope (TEM), respectively. It is shown that both the composites and the base alloys have the similar age-hardening curves and the same precipitation sequence: the higher the ageing temperature, the lower the aged peak hardness, and the faster the age-precipitation progress. The age-precipitation and the peak hardness are also accelerated and increased both for the composites and the base alloys with increasing the content of copper in the testing materials. Short mullite fibre not only increases the aged hardness of Al-Cu alloys, but accelerates the age-precipitation process of them. It is also found that GP zone formation is heavily suppressed by short mullite fibres, but the precipitation of theta(Al2Cu) is unchanged by the embeded fibres.