Effect of Microstructures on Deformation Behaviour of Aluminium Matrix Composites in Laser Bending

K C Chan,J Liang

doi:10.1155/tsm.34.43

Abstract

It is well known that the mechanical and deformation properties of metal matrix composites (MMCs) are related to their microstructures. However, less work has been carried out in laser bending to examine the dependency of microstructures of MMCs on deformation behaviour. In this paper, two aluminium-based metal matrix composites, Al2009/20 vol% SiCw and Al2009/20 vol% SiCp were investigated. A YAG laser was used to scan the composites both parallel and perpendicular to their rolling directions. It was reported that under the same processing conditions, a larger bending angle was obtained for the Al2009/SiCp composite. No significant change in microstructures was observed for both composites after bending. Experimental findings also revealed that for the particulate reinforced composite, a larger laser bending angle was obtained when the laser scanning direction was perpendicular to the rolling direction, whereas no significant difference was observed for the Al2009/SiCw composite. These phenomena were shown to relate to the shape and distribution of reinforcements.

Highlights

In the last decade, there have.been a considerable amount of experimental and theoretical investigations on laser forming (Vollertsen, 1994a; Vollertsen et al, 1995; Yau et al, 1998)
Experimental findings reveal that for the A12009/SiCp composite, a larger laserbending angle is obtained when the scanning direction of laser beam is perpendicular to the rolling direction
No significant difference is observed for the A12009/SiCw composite

Summary

INTRODUCTION

There have.been a considerable amount of experimental and theoretical investigations on laser forming (Vollertsen, 1994a; Vollertsen et al, 1995; Yau et al, 1998). Metal matrix composites (MMCs) are attractive for many structural applications because of their high specific strength, modulus of elasticity, thermal conductivity and structural stability (Hull and Clyne, 1996) They are relatively brittle and not easy to form at room temperature. It has been reported that a large bending angle can be achieved for an A12009/SiC composite and the bending angle is strongly related to the laser power, the processing velocity, and the number of irradiations They have examined the effect of sheet thickness, orientation and width on bending angle of an A16013/SiCp composite (Yau et al, 1996; Chan and Liang, 1999). A linear relationship between bending angle and threshold line energy is obtained It is, very worthwhile to further examine the effect of microstructures of MMCs in laser bending. A scanning electron microscope (SEM) was used to examine the microstructures of the specimens at different locations, before and after laser bending

Relationship Between Laser Bending Angle and the Number of Irradiations

Microstructural Examinations

Effect of Sheet Orientation and Reinforcement on Bending Angle

CONCLUSIONS