This study investigates the microstructure and mechanical properties of magnesium (Mg) containing alumina (Al 2 O 3 ) and copper (Cu) nanoparticles as hybrid reinforcements. For composite preparation, the amount of Cu was varied from 0.1 to 0.9 volume percent, whereas the amount of Al 2 O 3 was fixed at 1 volume percent. Mg and its composites were synthesized using powder metallurgy route incorporating energy-efficient microwave sintering followed by hot extrusion. Hybrid reinforcements in Mg matrix led to a grain size reduction, and the grain size decreased with increasing presence of secondary phases (reinforcements and intermetallics). Overall distribution of secondary phases within the matrix was observed to be uniform despite the formation of clusters. A significant improvement in microhardness was exhibited by all composite formulations when compared to pure Mg. The results also showed that yield and ultimate strengths were enhanced in all composite formulations under both tensile and compressive loading while tensile and compressive failure strains were compromised.

In the present study, the b transus of boron-modified Ti-6Al-4V alloy was found to be almost equivalent to that of the normal alloy, although there is a difference in interstitial element content large enough to produce significant change. Compositional analysis confirms the scavenging ability of the boride particles that are present in the microstructure toward the interstitial elements. This factor can successfully retard the a fi b phase transformation locally and increase the overall b transus of boron-added material.

Various ecological and economical concerns have spurred mankind’s quest for materials that can provide enhanced weight savings and improved fuel efficiency. As part of this pursuit, we have microstructurally tailored an exceptionally high-strength titanium alloy, Ti-6Al-2Sn-4Zr-6Mo (Ti6246) through friction stir processing (FSP). FSP has altered the as-received bimodal microstructure into a unique modulated microstructure comprised of fine acicular α″-laths with nano precipitates within the laths. The sequence of phase transformations responsible for the modulated microstructure and consequently for the strength is discussed with the help of scanning electron microscopy, transmission electron microscopy, and synchrotron X-ray diffraction studies. The specific strength attained in one of the conditions is close to 450 MPa m 3 /mg, which is about 22% to 85% greater than any commercially available metallic material. Therefore, our novel nano particle strengthened Ti alloy is a potential replacement for many structural alloys, enabling significant weight reduction opportunities.

No abstract

No abstract