含Si量对Mullite纤维/Al-Cu-Si复合材料及其基体合金时效行为的影响

用挤压铸造方法制备了Mullite/Al Cu Si复合材料。用硬度 (HB)测试仪、差示扫描量热仪 (DSC)和显微镜研究含Si量变化和Mullite纤维对Al Cu Si合金时效硬化行为的影响 ;元素Si、Mullite纤维以及二者同时存在对Al Cu Si合金时效析出序列的影响。结果表明 :Si和Mullite纤维明显抑制了Al Cu合金GP区的形成 ;随着含Si量增加 ,Al Cu Si合金的时效硬化过程加快 ;Mullite纤维对Al Cu和Al Cu Si合金的时效硬化过程都具有加速作用 ,同时提高了基体合金的时效硬度 ,但相对而言 ,Mullite纤维对无Si的Al Cu合金的时效硬化加速作用更为明显一些。

Effects of silicon content on ageing behaviours of Mullite/Al-Cu-Si composite and its base alloy

Short Mullite fibre reinforced Al 4.0Cu Si composites and their monolithic alloys with different Si content (0%, 2%, 5%, 7%) were fabricated by squeeze casting.The effects of Si content and short Mullite fibre on the age hardening behaviours of composites and the effects of Si, Mullite fibre and both of them on the precipitation procedure have been investigated by means of hardness(HB) measurement device, differential scanning calorimeter (DSC) and optical micrograph. It is shown that GP zone formation is heavily suppressed by either Si or Mullite fibre. With the increasing of Si content, the age hardening response of Al Cu Si ternary alloys is accelerated.The acceleration of ageing is observed both in Mullite fibre reinforced Al Cu composite and in mullite fibre reinforced Al Cu Si composite and the aged hardness of the testing composites is largely increased.Relatively speaking, the acceleration effect of mullite fibre in silicon free (no addition of silicon) Al Cu based composite is greater than that in silicon containing Al Cu Si based composites.