Effect of laser alloying with CoNiCrW powder on the properties of the AlSi7Mg surface layer

The surface of the AlSi7Mg alloy was alloyed with CoNiCrW powder using a continuous wave fiber laser with a wavelength of 1.07 mu m. The thickness of the alloyed layer is up to 4 mm. Its microstructure is radically different from the microstructure of the AlSi7Mg alloy. The basis of the microstructure of the alloyed layer is an alpha-solid solution based on aluminum, eutectic alpha + Si, and (Co,Ni)Al. The strengthening phases are aluminum oxides Al2O3, borides of the CrB type, and chromium carbides of various compositions. The alloyed layer is characterized by an average microhardness of 700 HV, an increased ability to resist elastoplastic deformation, and an increased wear resistance during abrasive wear tests. During wear tests under dry sliding friction conditions on a steel (0.2% C) counterbody, the alloyed layer is destroyed, which leads to an increase in mass loss during operation in such conditions.