Effect of processing parameters on the degree of infiltration of SiCp preforms by Al-Si-Mg alloys

The effect of the following processing parameters on the degree of infiltration of SiCp preforms by Al-Si-Mg alloys was investigated and quantified: SiC particle size, SiC type and Mg content in the aluminium alloy. These parameters were studied at two levels: 20 and 75 mum, GC and C, and, 3% and 6% Mg, respectively. The contribution of each of the aforementioned parameters and their interactions was determined using analysis of variance and the effect of the levels of each parameter was examined using surface response analysis. Analysis of variance (ANOVA) results show that particle size is the parameter that most significantly impacts the degree of infiltration, followed by magnesium content in the alloy. Surface response analysis shows-that regardless of-the type of SiC,the degree of infiltration increases with increase in magnesium content and that the increase rate in the degree of infiltration is higher for GC-SiC than that for C-SiC. For both SiC particle sizes, the type of SiC has no significant effect on the degree of infiltration; however, GC-SiC enhances infiltration. When using an alloy 3 wt.% Mg in the alloy, SiC particle size slightly affects the degree of infiltration. In contrast, an alloy 6 wt. % Mg significantly affects the degree of infiltration. An increase, in the degree of infiltration with increase in Mg content is observed for both particle sizes; however, in preforms with 75-mum powders, such increment is negligible compared to that for preforms with 20-mum powders. Accordingly, the optimum parameters for maximum degree of infiltration are: 20-mum powders, 6 wt.% Mg in the alloy and GC-SiC. (C) 2003 Elsevier Science B.V. All rights reserved.