Investigation into microstructural evolution, mechanical and tribological properties of an aluminum surface composite developed using a severe plastic deformation technique

Abstract

Aluminum based surface metal matrix composite was developed with 15% and 20% of TiCp reinforcement using multi-pass friction stirring process. The effect of TiC reinforcement and multiple FSP passes on microstructural evolution was characterized using optical, X-ray diffraction, electron microscopy, and electron backscattered diffraction techniques, while texture formation was analyzed using the neutron diffraction method. Hardness and tribological investigations were carried out to examine the mechanical behavior of the reinforced surface. A defect-free, uniformly reinforced composite surface with increased matrix-reinforcement interface was attained with 15% TiC after six passes. Hardness improved substantially to 215 HV due to the combined effect of zener pinning, grain refinement, uniformly dispersed reinforcement and increased dislocation density in the matrix. Better texture index was observed on the composite surface with Copper and S as dominating texture components. Significant wear resistance was exhibited by the composite at lower load due to strong adherence of TiC to the matrix, which however decreased with increase in loading conditions. Wear surface examination revealed that the mode of wear was predominantly abrasive.