Currently, the utilization of stainless steel and titanium alloys has been observed in diverse sectors such as aerospace, medical, and chemical plants. Furthermore, novel techniques for fabricating metallic samples using additive manufacturing have been devised. The coupling of materials in additive manufacturing processes is crucial due to the constraints of generating huge structures. This work investigates the bonding of austenitic stainless steel 316 and the Ti-6Al-2Sn-4Zr-2Mo alloy using the transient liquid phase bonding method using electron beam melting. A copper interlayer with a thickness of 25 microns was utilized for the bonding procedure. The process of transient liquid phase bonding was carried out within a vacuum furnace, maintaining a constant pressure, at temperatures of 890, 980, and 1050 degrees Celsius. The bonding was performed for durations of 60, 90, and 120 minutes. Following the bonding procedure, specimens were extracted from the core for microstructural analysis and subjected to metallographic procedures. The phases generated in the bonding region were examined using optical microscopy and electron microscopy with EDS equipment. The mechanical properties of the bonds were eva‎luated by tensile strength and microhardness tests, while the impact of surface roughness on the bonding surfaces was also examined. The findings indicate that as temperature and bonding time rise, the fusion zone area expands, causing the removal of Ti-Cu intermetallic compounds at the bond's center. Additionally, there is enhanced diffusion of titanium and iron elements towards one another, resulting in the creation of rigid and fragile Ti-Fe compounds. As a result, the hardness of the bonding area increases while its tensile strength drops. Specifically, the tensile strength decreases from 203 megapascals when held at 890 degrees Celsius for 120 minutes to 142 megapascals under the same conditions but at a temperature of 1050 degrees Celsius. Moreover, as bonding temperatures and periods are reduced, the copper concentration in the center of the bond increases, resulting in decreased hardness. As the temperature rises, the bonded area experiences a greater concentration of base metals due to the diffusion of copper. This leads to an elevation in hardness at a temperature of 970 degrees Celsius. Moreover, the intermetallic phase Ti-Fe exhibits a reduction in hardness as the temperature rises, although the Al-Fe phase, which is less hard, also experiences a loss in hardness. The study also examined the surface roughness of the bonds. The findings indicated that surfaces with reduced roughness exhibit superior bonding characteristics. Furthermore, the samples in this investigation achieved the lowest possible surface roughness. Ultimately, the analysis revealed that the sample subjected to a bonding process at a temperature of 890 degrees Celsius and a holding time of 120 minutes exhibited the greatest tensile strength. Subsequently, the sample bonded under the same holding time but at a temperature of 980 degrees Celsius showing a little lower tensile strength.

بهزاد نيرومند , مرتضي شمعانيان اصفهاني

علي اشرفي , قاسم عظيمي روئين