Effect of SiC concentration and strain rate on the compressive deformation behaviour of 2014A1-SiCp composite

The compressive deformation behaviour of 2014Al-SiCp composites containing varying amount of SiCp has been studied at different strain rates (10(-3) to 10(-1) s(-1)). The composite materials were prepared through stir-casting (vortex) method. The yield stress, Young's modulus, percentage elongation and fracture stress were measured from the true stress-true strain plots. The Young's modulus of the materials was found to increase with increase in SiCp content. But the yield stress and the fracture stress do not follow any definite relationship with SiC content. The composite, containing 15 vol.% SiCp, exhibits minimum stress values irrespective of strain rates. The composite, containing either less or greater than 15 vol.% SiCp, exhibited almost same yield stress as that of the alloy. The elongation, in general, decreases with increase in SiCp. It was further found that the above parameters do not follow any definite trend of variation with strain rate for any investigated materials. The strain-hardening exponent and the strain rate sensitivity were determined for each of the materials at different strain rates. It was noted that the plastic strength coefficient also follows the same trend of variation with SiCp content irrespective of strain rate; but the strain-hardening exponent increases marginally with increase in SiCp content. The strain-hardening exponent also remains invariant to strain rate. The strain rate sensitivity is noted to be very low. However, within this variation, the composite containing 15 vol.% SiC exhibits the minimum value of strain rate sensitivity. This also suggests that at room temperature, the cast alloy and/or composites are almost insensitive to strain rate. (c) 2006 Elsevier B.V. All rights reserved.