Microstructural characterisation of novel 6351 Al–Al₄SiC₄in-situ composite

Abstract

6351 Al–Al₄SiC₄ composite has been developed through stir casting route by incorporation of fine TiC powder in 6351 Al melt. Simultaneous effects of the generation of in-situ particles (Al₄SiC₄ and Al₃Ti) and grain refinement were observed. The in-situ generated Al₄SiC₄ particles were found to act as nucleation sites for primary α (causing grain refinement) along with engulfment effect promoting uniform particle distribution. As the volume fraction of Al₄SiC₄ particles increased, the dendritic solidification was suppressed (more equiaxed grains appeared) and overall grain size of the matrix decreased. Besides, the precipitation of Al₃Ti occurred at the dislocation enriched region. Accordingly, hardness of the composite was improved with increasing content of Al₄SiC₄ particles.

Keywords:

• Composite
• in-situ Al₄SiC₄
• Grain refinement
• Engulfment

Authors acknowledge the support of Mr S. C. Das, Mr M. K. Das and Mr P. S. Banerjee of National Institute of Technology Durgapur, India, in various occasions during this investigation. Authors are thankful to Dr. A. Saha, Principal Scientist, CSIR-Central Mechanical Engineering Research Institute, Durgapur, India and Dr R. Maiti, Senior Scientific Officer, Indian Institute of Technology, Kharagpur, India, for necessary support in SEM investigations. Authors are also grateful to the Director, National Institute of Technology Durgapur, India, for necessary financial and administrative support.