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

Laser alloyed layers of Cu–Fe–Al–Si were prepared using an 8 kW $CO_2$ 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 $DO_3$ 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