HIGH-STRENGTH ALUMINIUM ALLOYS THROUGH RAPID SOLIDIFICATION PROCESSING.

Abstract

The techniques of rapid solidification are over two decades old and their beneficial effects, viz. , refinement of grain size, extension of solid solubility limits and formation of metastable intermediate phases as well as metallic glasses are now well established. After reviewing the various principles and techniques available to quench or rapidly solidify metallic melts at very high cooling rates, methods of consolidating the rapidly-solidified particulates are described. The types of microstructures developed and their control are discussed. A critical review of the literature reveals that the above-mentioned metastable effects of rapid solidification either singly or jointly lead to improved properties of the materials. New alloys can now be designed from first principles to achieve high specific strength and high specific modulus of elasticity. The development work done in aluminium alloys is reviewed with special reference to the Varanasi investigations.