CREEP BEHAVIOR OF ULTRASONICALLY PROCESSED AZ91-NANO Al2O3 COMPOSITE

Abstract

The goal of this study is to evaluate core principles and to establish quantitative basis for the effects of ultrasonic processed AZ91-nano Al2O3 composite on the microstructure and creep properties. The nano composite was fabricated by adding 0%, 0.5%, 1% and 3% by weight Al2O3 (50 nm) to AZ91 alloy assisted by ultrasonic vibration. The ultrasonic vibrations distribute the nano particles uniformly in the melt, increases homogeneity and reduce segregation. The microstructures and mechanical properties of the produced composite are characterized Indentation creep tests are performed on the as cast and prepared nano composites at three different temperatures of 448 K, 473 K and 498 K and three different stresses of 222 MPa, 305 MPa and 388 MPa. Nano alumina additions increase the creep resistance of AZ91 alloy matrix with AZ91/3% alumina exhibiting the highest resistance. The creep behavior and dominant creep mechanism is studied further.