The last half dozen years have seen a rapid growth in research on the effects of laser surface melting (LSM) and rapid self quenching on metallic systems. Modification of surface sensitive behavior has been demonstrated in a number of alloys systems. Even more recently there has been a renewed interest in laser surface alloying (LSA)—the melting/rapid quenching of predeposited film plus metal substrate.

The coupling process between metallic surface and focussed beam is sensitive to pre-irradiation surface quality. The resulting LSM or LSA area may be uniform as a result of controlled processing, or very nonuniform due to local variations in the coupling phenomena. Four categories are identified as the major causes for nonuniformities: topographical inhomogeneities, structural/chemical inhomogeneities, impurity effects and interference effects. If LSM or LSA processing is to move out of the laboratory and into the real world the significant of these differences will have to be addressed.