The Effect of Bonding Temperature on the Microstructural and Mechanical Properties of Transient Liquid Phase Bonded Commercially Pure Ti Joint

Abstract

Commercially pure Ti (AMS 4902) was joined using the transient liquid phase bonding technique. The joining process was implemented at various temperatures of 820, 860, 900, and 1000 °C for 90 min under a vacuum atmosphere of 7.99 Pa. The microstructural investigations were carried out comprehensively using scanning electron microscopy equipped with the EDS elemental detector. The mechanical properties were characterized using the microhardness and shear strength tests. Strength properties in terms of ultimate shear strength and ductility were presented as force-extension diagrams. The presence of eutectic intermetallics in the joint centerline indicated that isothermal solidification was not achieved at low bonding temperatures. However, the increase in temperature to 1000 °C resulted in a fully isothermal solidified joint. The elemental gradients between the bonding centerline and the base metal leveled off at high temperatures of 900 and 1000 °C, where the solubility of Ti increased in the Cu crystal structure. A higher hardness of 270 HV with a uniform gradient was also observed across the joint produced at high temperatures of 900 and 1000 °C. A combination of high strength and ductility was obtained for the samples fabricated at 900 and 1000 °C bonding temperatures.