Mechanical properties of laser-processed pre-oxidized Ma956 alloy and 3YSZ ceramic joints via reactive air brazing

In order to improve the mechanical properties of brazed joints between Ma956 alloy and 3YSZ ceramics, a composite treatment of laser processing and pre-oxidation was adopted to prepare a periodic groove structure covered with an Al₂O₃ layer on the surface of Ma956 alloy, so as to inhibit the oxidation of matrix elements and improve the performance of joints. The treated Ma956 alloy was joined to 3YSZ ceramics via reactive air brazing. The results show that with the increase in the number of laser processing passes, the shear strength of the joint first increases and then tends to stabilize. When the laser processing is performed 100 times, and the groove depth reaches about 39.9 μm, the joint strength attains a maximum value of 73.1 MPa, and the fracture mode transforms from brittle fracture to ductile fracture. Finite element analysis results show that the reaction layer on the alloy side is the most stress-concentrated region of the joint. The laser-processed grooves can convert the normal stress of the reaction layer from tensile stress to compressive stress, while reducing the shear stress, thereby effectively inhibiting the pullout of brazing filler metal and crack propagation and significantly improving the shear strength of the joint.