Although various processes are classified as RSPs, only a few have been used and evaluated for Al–Li production. This allows for the T 1 phase to precipitate in a more homogeneous manner, resulting in a better balance of strength and ductility. One of the main attractions of using the RSP process on Al–Cu–Li alloys is the ability to induce solute trapping, hindering the formation of dendrites and cells which serve as heterogeneous nucleation sites for precipitates. Cellular structure obtained through rapidly solidified gas atomized aluminium–lithium alloy powder. The present investigation was undertaken to study the effect of laser parameters on the microstructures resulting from RSP by laser surface melting.įig. Therefore the background of this surface treatment is a suitable knowledge of the relationships between the laser treatment parameters, the induced thermal transient and the influence of thermal conditions during solidification on resulting microstructure. However the microstructure resulting from the RSP by laser surface melting is strongly dependent on the thermal transient induced into the surface layers. The range of attainable surface modifications is enlarged by the possibility to introduce other elements by surface alloying during melting 2. High-density heating devices, such as laser beams, allow rapid melting and subsequent solidification to be obtained in surface layers, producing typical effects of RSP in a surface treatment. Chemical homogeneity deriving from non equilibrium-extended solutions offers opportunities for subsequent heat treatments to produce the final microstructures of desired properties.
Fine grained structures generally have improved strength and reduced anisotropy. Rapid solidification processing (RSP) commonly results in departures from conventional microstructures, giving an improvement of grain refinement and chemical homogeneity 1. Sebastiano RUDILOSSO, in Rapidly Quenched Metals, 1985 1 INTRODUCTION
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