Effect of interfacial thickness and residual stress on the mechanical property of the alumina–stainless steel braze joint interface

Polycrystalline alumina and stainless steel were brazed at 900, 1000 and 1100 °C. Microstructural and mechanical property of the interface have been correlated. Interface was characterized by scanning electron microscopy and transmission electron microscopy. SS interface consists of FeTi and Fe35Cr13Ni3Ti7 phase whereas TiO, Al2TiO5 and Cu3Ti3O phases have been found at the Al2O3 interface. Shear strength of the joints was evaluated for different samples and maximum strength of 94 MPa has been obtained. Residual stress produced due to the coefficient of thermal expansion mismatch between the substrate and the reaction products at the interface, has been measured by X-ray diffraction technique. Thickness of the interface and the microstructural arrangements of the different reaction products at the interface play a vital role in determining the mechanical property of the joint. Optimum process parameters have been determined.