Development of Nanostructured Al-Si-Fe Based Bulk Alloys from Atomized Powders

초록

Al-Si-Fe alloy has been known as one of promising candidate materials to use it in the field of automobile industry because of its light-weight and reasonable wear resistance. Generally, powder metallurgy technique has been used to produce a near-net shaped component using this particular alloy system, especially for engine parts. Currently, three kinds of processing steps, pre-compacting, sintering and subsequent hot forging were adapted to produce a near-net shaped part. In the present study we have tried to make a bulk Al-Si-Fe based alloy without sintering process since sintering and forging process of the present alloy has been carried out at temperatures above 0.8Tm(melting temperature) resulting in severe coarsening of dispersoids and grain growth. The nominal composition of the present alloy was Al-10Si-5Fe-4Cu-2Mg-1Zr(wt%) produced by gas atomization process. We chose Cu and Mg as additional alloying elements to reduce a eutectic reaction temperature and to expect increased volume fraction of intermetallic dispersoids leading to improved mechanical properties. From the experimental results obtained we have successfully produced bulk Al-10Si-5Fe-4Cu-2Mg-1Zr alloy with high volume fraction of nano-sized intermetallic phases in the low temperature region and its mechanical property was superior to the same alloy produced by three processing steps described above. Microstructure and mechanical property of the present alloy will be correlated with volume fraction of intermetallic dispersoids, grain size and phase analysis results obtained.