Influence of lanthanum on enhancement of mechanical and electrical properties of Cu-Al2O3 composites

Two kinds of Cu-Al2O3 composites (with and without La) were prepared via mechanical alloying-spark plasma sintering (MA-SPS) method. Microstructure, mechanical properties and electrical resistivity were investigated systematically using metallography, scanning electron microscopy, transmission electron microscopy, mechanical and electrical properties testing. The results indicate that an appropriate amount of La can homogenize the distribution of Al2O3. As such, yield strength, ultimate tensile strength and elongation of Cu-Al2O3-La are greatly increased. Some semi-coherent interface between Cu and Al2O3 is found, which means a low interface energy. The grain shape of Cu changes to irregular band with the addition of La. This change results in a density decrease of grain boundary and reduces electrical resistance. Lanthanum may exist in the form of La2O3. (C) 2019 Chinese Society of Rare Earths. Published by Elsevier B.V. All rights reserved.