Microstructure, Mechanical Properties, and Thermal Stability of Al-Al2O3 Nanocomposites Consolidated by ECAP or SPS from Milled Powders

Ultrafine-grained Al matrix nanocomposites, reinforced with Al2O3 nanoparticles, were produced from milled powders, either by equal channel angular pressing (ECAP), at room or high temperature, without back pressure, spark plasma sintering (SPS). Their microstructures, mechanical properties (compression, hardness, and sliding wear), thermal stabilities (thermally induced softening cracking) compared, the advantages limitations of each process discussed on a scientific but also practical point view. For most successful set parameters, yield stress in compression reached 380 MPa, HV = 139, remained stable up to 500 °C, resistance wear was comparable that 5083, better than 7075-T6. While samples consolidated temperatures (by ECAP SPS) showed good stability, those temperature prone thermally cracking, which related trapped pressurized gases.