In this study, microstructure and mechanical properties of Cu-based amorphous alloy matrix composites consolidated by spark plasma sintering (SPS) equipment were investigated. Amorphous alloy powders were mixed with 10∼40 vol.% of pure Cu powders, and were consolidated at 460°C for 1/2 minute under 300 or 700 MPa. The consolidated composites contained Cu particles homogeneously distributed in the amorphous matrix, and showed a considerable plastic strain, whereas their compressive strength was lower than that of the monolithic amorphous alloys. The compressive strength and plastic strain of the composites consolidated under 700 MPa showed 10∼20% and two times increases, respectively, over those of the composites consolidated under 300 MPa. The increase in consolidation pressure could play a role in sufficiently bonding between prior amorphous powders, in preventing micropores, and in suppressing the crystallization, thereby leading to the successful consolidation of the high-quality composites. Microfracture mechanisms were investigated by directly observing microfracture processes using an in situ loading stage. Cu particles present in the composites acted as blocking sites of crack propagation, and provided the stable crack growth. These findings suggested that the composites consolidated by the SPS presented new possibilities of application to structural materials or parts requiring excellent mechanical properties and large sizes.

Nanostructured and conventional titania (TiO2) coatings were thermally sprayed using air plasma spray (APS) and high velocity oxy-fuel (HVOF) processes. The fatigue and mechanical properties of these coatings were investigated. The fatigue strength of coatings deposited onto low-carbon steel showed that the nanostructured titania coated specimens exhibited significantly higher fatigue strength compared to the conventionally sprayed titania. SEM analysis of fracture surfaces revealed valuable information regarding the influence of these coatings on the performance of the coated component. Analysis of surface deformation around Vickers indentations was carried out. This investigation gives new understanding to the nature of fatigue and deformation of these coatings.