Reza Soltani

Laser surface treatment of AZ91 magnesium alloy presprayed with WC–Co

In this study, the surface of AZ91 magnesium alloy plasma sprayed with WC–12 wt-%Co powder was melted by pulsed Nd:YAG laser. Microstructure, chemical composition and phase analyses of the treated layers were studied by utilising a scanning electron microscope equipped with energy dispersive spectroscopy, X-ray diffraction technique and a microhardness testing machine. Laser treated layers showed much finer structure compared to that of the original base material with suitable distribution of WC particles. Microhardness of melted zone achieved at optimum condition was ∼3.5 times higher than that of the base material. In addition, the presence of WC particle and refined structure reduced the wear rate to less than half in the laser treated layer.

Microstructural and Hardness Study of Pulsed Nd:YAG Laser Surface Alloyed Aluminum with Iron

In the present study, the feasibility of the formation of surface layers containing hard iron aluminides on AA6061-T6 aluminum via pre-plasma spraying with iron and subsequently double surface melting by pulsed Nd:YAG laser is studied. The effects of single and double laser surface melting on microstructure, phase formation, and hardness of the treated layers are examined. Single-step laser treatment resulted in the presence of undissolved iron particles surrounded by lump-like Al5Fe2 and needle-like Al3Fe intermetallic compounds. Double laser surface melting dissolved the retained undissolved irons and resulted in the formation of Al-Al3Fe eutectic structure. Microhardness profiles along cross section and top surface of the treated layers indicated that laser surface alloying with iron enhanced the hardness of the aluminum to more than twice of that of the base material.

Pulsed Nd:YAG laser surface alloying of AZ31 magnesium with nickel for improved wear and corrosion resistance

The present paper reports studies of pulsed Nd:YAG laser surface  alloying of AZ31 magnesium preplasma sprayed with nickel 5% aluminum powder. Mechanical properties like microhardness and wear resistance as well as corrosion resistance of the surface alloyed layers are studied. Detailed characterization of the laser surface alloyed layers regarding microstructure and phase analysis revealed formation and distribution of Mg2Ni  intermetallic phase in grain refined α-Mg matrix. Microhardness test demonstrated that hardness of the alloyed layer increased to 290 HV as compared with 55 HV of the AZ31 base material. Furthermore, pin on disk wear test and Tafel polarization measurement showed that laser surface  alloying with nickel led to a considerable improvement in both wear and corrosion resistance for AZ31 magnesium.