EFFECT OF CNT/TIB2 PARTICLE ON MECHANICAL, METALLURGICAL BEHAVIOUR OF MAGNESIUM (AZ91D) COMPOSITES

Carbon Nano tubes (CNT) and Titanium di Boride particles (TiB2) with different weight percentages reinforced composite magnesium alloy (AZ91D) were fabricated and the impact of changes in the mechanical and metallurgical properties of composites was assessed. Different weight percentage strengths of CNT (1.5 percent) and TiB2 particles (5 %, 10%, 15 %) were applied to AZ91D grade magnesium alloy for various stir casting system process parameters in this study. For reinforcement-matrix interfacial reactions, SiC and Al2O3 were also added. The composites with 10% TiB2 and (1.5 % CNT+1 % SiC+1% Al2O3) reinforcement show high hardness, whereas other reinforcements show increased elongation. The presence of elements revealed by energy dispersive X-ray spectroscopy also characterizes the composites using optical and scanning electron microscopy.

Investigation of in situ synthesized TiB2 particles in iron-based composite coatings processed by hybrid submerged arc welding

In the study for this contribution, production of in situ synthesized TiB2 particles in iron-based composite coatings using four different submerged arc welding powders (fluxes) containing increasing amounts of ferrotitanium and ferroboron with S1 welding wire, were targeted. For this purpose, coating deposition was carried out to improve the hardness and wear properties of the AISI 1020 steel surfaces using hybrid submerged arc welding. In hybrid submerged arc welding, the welding pool is protected by both welding powders and an argon gas atmosphere. To examine the composite coatings, visual, chemical, microstructural analyses and hardness and wear tests were carried out. With the use of increasing amounts of ferrotitanium and ferroboron in the welding powders, it was observed that the microstructure of the coatings changed in terms of TiB2 particle geometries such as rectangular and hexagonal; volume fractions of TiB2 particles in the coating microstructures increased; hardness values of coatings were enhanced from 34 HRC to 41 HRC; the wear resistance of the coatings improved, and worn surface images of the coatings caused by the counter body changed from continuous with deep scratches to discontinuous with fine scratches and crater cavities.

Cold Forming of Al-TiB2 Composites Fabricated by SPS: A Computational Experimental Study

The mechanical response and failure of Al-TiB2 composites fabricated by Spark Plasma Sintering (SPS) were investigated. The effective flow stress at room temperature for different TiB2 particle volume fractions between 0% and 15% was determined using compression experiments on cylindrical specimens in conjunction with an iterative computational methodology. A different set of experiments on tapered specimens was used to validate the effective flow curves by comparing experimental force–displacement curves and deformation patterns to the ones obtained from the computations. Using a continuum damage mechanics approach, the experiments were also used to construct effective failure curves for each material composition. It was demonstrated that the fracture modes observed in the different experiments could be reproduced in the computations. The results show that increasing the TiB2 particle volume fraction to 10% results in an increase in material effective yield stress and a decrease in hardening. For a particle volume fraction of 15%, the effective yield stress decreases with no significant influence on the hardening slope. The ductility (workability) of the composite decreases with increasing particle volume fraction.