Effect of Ultrasonic Assisted Solidification on Microstructure and Mechanical Properties of Nb-Si Alloy

Nb-Si alloy is an ideal material to replace Ni-based superalloy as the hot end component of aerospace engine. In this study, the microstructure and the room temperature fracture toughness of the Nb-16Si-20Zr-2C alloys before and after ultrasonic treatment were studied. It is found that the application of ultrasonic wave changes the phase content in the alloy. Under the action of ultrasonic wave, a large number of primary silicides phases are precipitated, and the shape of the primary silicide is a regular polygon with sharp corners. Therefore, after ultrasonic treatment, the room temperature fracture toughness of the alloy decreased by 24.1 %, mainly due to the increase of the brittle phase and the sharp edge of the brittle phase splitting the continuous Nbss phase matrix, resulting in a decrease in the room temperature fracture toughness of the material.