Role of CeAl11O18 in reinforcing Al2O3/Ti composites by adding CeO2

Abstract

AbstractThis work discusses the reinforcement effect of elongated CeAl11O18 phase on multifunctional Al2O3/Ti composites by adding CeO2 to inhibit interfacial reaction and strengthen interface for inducing optimized performances. For this purpose, Al2O3/Ti composite with different contents of CeO2 was fabricated and the microstructure, mechanical and electrical properties were studied. Results indicated that after CeO2 was added, elongated CeAl11O18 phase was formed within these composites. Owing to inhibited interfacial reaction between Al2O3 and Ti, Ti content was increased and compositions of composites were calculated using Rietveld method based on X‐ray diffraction patterns. Attributed to the strengthening and toughening effects of CeAl11O18 phase, 2 mol% CeO2 added composite showed the highest flexural strength and fracture toughness of 576 MPa and 5.15 MPa·m1/2, which increased by 21% and 20% compared to Al2O3/Ti composite without CeO2 addition. In this case, crack bridging by both Ti and CeAl11O18 particles was the major toughening mechanism and the additional fracture toughness caused by CeAl11O18 toughening effect reached a maximum. The role (crack bridging or particle pull‐out mechanism) of CeAl11O18 in toughening Al2O3/Ti composites depended on the aspect ratio of these elongated particles, which was directly related to CeO2 content. Because of the inhibition of interfacial reaction and the increase in Ti content, excellent electrical resistivity of composites after CeO2 addition was maintained in spite of the formation of insulated CeAl11O18 phase. All samples showed relatively low electrical resistivity of ~10−3 Ωcm.