Characterization of defects in laser treated copper alloys

To understand how laser induced defects form, what metallurgical variables influence them, and how they can be eliminated, the microstructures and defects produced by laser treating several copper alloys were characterized. Both pores and cracks were observed in the resolidified laser melts of some alloys. Pores form only in regions which solidify by a cellular dendritic mechanism. Crack formation tendency is a function of composition, processing conditions, and prior texture. This work reveals that laser induced defect formation can be minimized by control of base material composition and texture and by establishing plane front resolidification conditions after laser melting