Microstructure evolution in laser alloyed layer of Cu-Fe-Al-Si on Cu substrate

Abstract

Laser alloyed layers of Cu-Fe-Al-Si were prepared using an 8 kW CO₂ laser on copper substrate and a detailed TEM investigation of the cross-section microstructure was carried out. This paper elucidates on the sequence of evolution of various phases constituting a complex microstructure due to non-equilibrium solidification of the laser alloyed layer. The formation of micron size Fe-rich globules having DO₃ structure within Cu-rich fcc matrix suggests access to a submerged miscibility gap during the laser processing. The solute rejection processes during later stages of solidification and solid state cooling result in the evolution of submicron size Cu-rich dispersoids inside the Fe-rich globules and the Fe-rich nanoscale fully coherent precipitates within the surrounding Cu-rich matrix.