Al/Ti5Si3-Al3Ti composite prepared via in-situ surface coating of Ti using tungsten inert gas welding

Abstract

This study tried to enhance simultaneously the surface micro-hardness as well as corrosion resistance of Ti by preparation of in-situ Al/Ti5Si3–Al3Ti composite using TIG process and 4043 Al filler alloy. The alloyed layers were characterized using X-ray diffraction (XRD) and field emission scanning electron microscopy (FESEM). ASTM E384-HV and X-ray diffraction via ψ analysis were employed for determination of micro-hardness of prepared samples, and residual stresses at the interface of prepared coatings. To study the corrosion behavior of the final products used from NaCl 3.5 wt% electrolyte by potentiostat analysis. Surface coating was carried out by consideration of dilution ratio and passes number as operational variables. Results showed that, by increasing of pass number and filler injection rate, the thickness of Ti5Si3 layer at the interface gradually increased. In addition, Al3Ti phase formed far from the interface. In these conditions, the corrosion resistance and micro-hardness of prepared coatings were enhanced through the cladding. Analysis of residual stresses on the prepared coating at optimum condition confirmed the evolution of tensile residual stresses equal to 290 ± 40 MPa at the center line of fusion zone. The prepared sample with the highest surface micro-hardness as well as corrosion resistance was selected as optimum condition for investigating the effect of time (from 1 to 20 h s) and temperature (550–600 °C) through annealing process. Annealing treatment for 10 h s at 600 °C, not only enhanced the amount of Ti5Si3–Al3Ti phases and provided the possibility of the formation of adhesive and uniform Ti5Si3 layer at the interface of the clad/substrate but also raised the micro-hardness and corrosion resistance of the prepared coatings and determined as optimum condition.