Fabrication and Mechanical Properties of Al-Based In Situ Nano-Composites Reinforced by Al₂O₃ and Intermetallic Compounds

Abstract

The Al-based ex situ and in situ composites are fabricated by totally same staring materials. No pore was observed on their cross sections. The fabricated Al-based ex situ and in situ composites are reactive hot pressed with continuously applied pressure of 60 MPa at 620 and 700°C for 5 min respectively. The reactive hot pressed ex situ composites contain homogeneously distributed metal oxides such as ZrO₂, Ta₂O₅, Nb₂O₅, WO₃ and MoO₃ with nano or submicron sizes. On the other hands, the reactive hot pressed in situ composites contain homogeneously distributed θ-Al₂O₃ and intermetallic compounds such as Al₃Zr, Al₃Ta, Al₃Nb, Al₅W, Al₁₂W and Al₁₂Mo. It was found that the ex situ composites have a limited range of the mechanical properties such as Young’s modulus and hardness even they contain homogeneously distributed metal oxide particulates with nano or submicron sizes. However, the reactive hot pressed in situ composites present relatively various range of the mechanical properties. It was experimentally confirmed that the in situ composites fabricated by the reactive hot pressing technique is useful for fabricating a high performance structural materials.