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The Cu base composites play a key role in multiple industrial applications such as bearing materials and carbon brushes owing to their superior thermal, mechanical and tribological features. Therefore, in the present investigation, synergetic influence of nano titanium carbide (TiCnp) and graphite particles (Grp) on tribological behaviour of Cu base self-lubricating composites have been studied. The composites with fixed 5wt% of Grp and varying amounts (1.5wt% to 4.5wt%) of TiCnp were prepared via flake powder metallurgy (flake PM) technique. The sintered samples were characterized by different techniques for phases, physical, morphological and mechanical properties. Pin-on-disc (POD) tribotester has been used to analyse the tribological behaviour of composites in dry sliding condition by varying loads (10 N to 30 N) and sliding velocities (0.75 m/s and 1.5 m/s) for a fixed sliding distance of 2000 m. The results indicate the successful formation of Cu-Grp and TiCnp-reinforced Cu-Grp composites. With addition of Grp, the wear rate and coefficient of friction (COF) of Cu matrix is reduced. The wear rate is further reduced with the incorporation of TiCnp particles. But, the COF shows the enhancement. The composite having 5wt% Grp–4.5wt% TiCnp shows the minimum wear and maximum hardness. The energy-dispersive spectroscopy (EDS) elemental mapping of worn surfaces indicates that TiCnp mechanically interlocks the graphite at the interface and prevent its removal and reduces the wear rate. The worn surface investigation also shows that the dominant mechanism of wear for pure Cu sample is delamination in nature. However, the mechanism of wear for TiCnp-reinforced composites is a combination of abrasive and delamination wear. [ABSTRACT FROM AUTHOR]

In the present work, Al3Zr/Al composite was fabricated through the in situ route. The fabricated composite was isothermally forged in the temperature and deformation rate range of 300-450 °C and 0.001-1 s−1 to a true strain of 0.69. The flow stress behavior of the forged specimen decreased with the increase in temperature and decrease in the deformation rate. The kinetic rate calculation indicated an average hot deformation activation energy of 196 kJ/mol. The workability map showed a maximum power dissipation of 43% in a narrow working zone of 442-450 °C, 0.001 s−1. Another working zone II with an efficiency value of > 34% is observed in 386-403 °C, 0.047-0.02 s−1. Microstructural instabilities during hot forging are mostly observed at lower temperatures and higher strain rates regions, which are micro-crack, flow localization, particle cracking, and debonding. The EBSD analysis indicated a higher fraction (≥ 55%) of strain-free grains in the peak dissipation efficiency region (400 °C, 0.1 s−1, and 450 °C, 0.001 s−1). The boundary misorientation analysis confirmed the occurrence of dynamic recovery (DRV) and continuous dynamic recrystallization (CDRX) during hot forging. Dynamic softening is also supported by PSN and is dominant in the Al3Zr and matrix interface. [ABSTRACT FROM AUTHOR]

In the current work, microstructure-mechanical property correlation in Al-Si/ Mg2Si-xwt.% TiB2 (x = 0, 1, 3 and 5) insitu hybrid composites fabricated by cooling slope casting has been investigated. The microstructure and mechanical properties of these developed materials have been studied via different characterization techniques. Results indicate that the cooling slope casting and insitu generated TiB2 particles significantly reduce the grain size of α-Al (about 51%) and morphology of Mg2Si phases (46%). The cooling slope casting method promotes the dendrite fragmentation due to shearing action, emerging in developing non-dendritic and globular structures. The TiB2 particles acts as a nucleation site of Mg2Si phase and also help refine the Mg2Si phase. The tensile strength, percentage elongation and hardness of the Al-Si/Mg2Si-TiB2 hybrid composites are increased with an increased wt.% of TiB2 particles and maximum improvement 28% in tensile strength, 55% in percentage elongation and 30% hardness is observed in the case of Al-Si/Mg2Si-5wt.% TiB2 hybrid composite than of Al-Si/Mg2Si composite. The tensile fracture surface of hybrid composite is also correlated with the tensile properties and it has quasi-cleavage fracture. These composites could be promising materials to make the components for automotive and aerospace sectors. [ABSTRACT FROM AUTHOR]

The present work has used pin on disc tribometer at atmospheric conditions to examine dry sliding tribological properties of Zn–Al (ZA) alloy and ZA/ZrB2 composites at varying reinforcement of ZrB2 particles (0, 3, 4.5, 6 and 9 vol%), load (10–50 N) and sliding distance (1000–5000 m). The composites were fabricated using stir cast insitu technique and characterized (in terms of morphological and mechanical) by different techniques. Tribological behaviour of composites has been analyzed in terms of wear volume and frictional coefficient. Scanning electron microscopy, surface profilometer and atomic force microscopy tools were employed to analyze the worn surface to show the mechanism of wear to substantiate the obtained results. Obtained results suggest that the insitu formed ZrB2 particles refine the microstructure and improve the mechanical properties of composites. However, at 9 vol% of ZrB2, the matrix grains are refined by 48% and the hardness value is improved by 68% compared to ZA alloy. As the volume percentage (vol%) of ZrB2 rises, wear rate decreases while coefficient of friction (CoF) surge. However, linear rise in wear and CoF with rise in load and sliding distance. At lower load, wear mechanism is oxidative, while at high load, it converts to oxidative-metallic. Composites with 9 vol% ZrB2 show approximately 80% reduction in wear at load (50 N) and sliding distance (5000 m) compared to ZA alloy. These fabricated composites could be utilized for those applications where less wear and high CoF along with high strength are required. [ABSTRACT FROM AUTHOR]

The lymphangioma is a benign hamartomatous, uncommon, hyperplasia of lymphatic system. It is common in head and neck but rarely found in oral cavity. In oral cavity, it occurs mostly in tongue. In this article, we will report a case of lymphangioma circumscriptum of lip in a young male which is unusual. [ABSTRACT FROM AUTHOR]