High Strain Rate Superplasticity of a ?–Si_3N_4 Whisker Reinforced Pure Aluminum Composite

摘要

?-Si_3N_4 whisker reinforced aluminumcomposites was fabricated by squeeze casting and an effect ofthermomechanical processing and Mg on the High Strain RateSuperplasticity (HSRS) were investigated, The ?-Si_3N_4w/Al-0Mg composite produced about 200 percent elongation at thestrain rate of about 0.1(1/s) and the in value of 0.47 at903~913K. Thep-Si_3N_4w/Al-0Mg has the liquid temperatureof 913K 50 that the HSRS could produce without any liquidphases and melting temperature of the p-Si_3N_4/Al-0Mg alloycomposites and the optimum temperature of the composite atwhich maximum total elongation is obtained decreasesaccording to magnesium content, and TEM observationindicates that The ?-Si_3N_4w/Al-Mg have a fine grain ofabout 2~3 #mu#m and that the whisker does no react with Mg atthe interfaces in the case of the ?–Si_3N_4w/Al-0Mg and the ?-Si_3N_4w/Al-3Mg.