High Strain Rate Behavior of Stir Cast Hybrid Al-Si Matrix Composites Using Split Hopkinson Pressure Bar

Aluminum alloy based metal matrix composites are widely used in different engineering applications that are subjected to dynamic loading conditions. In the present study, aluminum alloy Al-Si7Cu3Mn0.5(LM27) composites are manufactured by a stir casting route with two different weight percentages and different size of SiC and TiO2. The reinforcement particles of 15 µm and 115 µm sizes are reinforced in a concentration of 3wt. % and 12wt. %. Split Hopkinson pressure bar is used to evaluate dynamic compressive behavior of the composites at the strain rate of 700, 1500 and 2500 s−1. Microstrucutral examination of fine size reinforced composites exhibited the formation of globular silicon that is arranged around the particles. Micro-hardness of the particle–matrix interface of the fine particle reinforced composite is higher in comparison to composite reinforced with coarse particles. At the strain rate of 700 s−1, at higher concentration of reinforcement particles the fine particles reinforced composites exhibit maximum strength whereas lower concentration of fine particle reinforced composite showed the maximum strain. Strain sensitivity is exhibited by all the composites and strength shows an increasing trend with an increase in the strain rate. The fine particles reinforced composites exhibited maximum flow stress at higher weight percent of reinforcement particles whereas maximum strain is found at lower weight percent of fine particles. The dynamic compressive behavior of composite is found dependent on the degradation of elastic modulus, stress localization phenomena and debonding characteristics.