Effect of sintering temperature on microstructure characteristics and damping capacity of multilayer 316L stainless steel hollow spheres/A356 alloy composites reinforced by NiTi alloy sheets

Abstract

In order to improve the damping capacity of aluminum alloy, multilayer 316L stainless steel hollow spheres/A356 alloy composites reinforced by NiTi alloy sheets were successfully prepared under different sintering temperatures using a pressure casting method. The experiments performed in the current work confirmed that the microstructure and properties of composites are affected by sintering temperatures. Compared with the composites sintered at 620, 660, 680 and 700°C, the composites sintered at 640°C have the lowest density of 2.42 ± 0.21 g/cm3, and the highest porosity of 43.1 ± 2.1%. NiTi alloy sheets are completely reacted with the matrix when sintering temperature is higher than 640°C, while the remaining NiTi alloy sheets is visible in the composites sintered at 620°C and 640°C. The higher plateau stress (125.06 ± 2.27 MPa) and higher loss factor (0.032 ± 0.006) of the composites sintered at 640°C are dependent upon such the remaining NiTi alloy sheets and high porosity. The structure of alloy sheet is beneficial to the uniform propagation of stress, and blunts the crack propagation, which can improve the internal friction and compressive property of composites.