Papers by Author: Norhamidi Muhamad

Abstract: This paper presents the processing of Nickel Titanium (NiTi) alloy from elemental powders of Nickel and Titanium by conventional powder metallurgy process. Two batches of feedstock containing 2 different formulations (1) Ti-50.4at% Ni and (2) Ti-50.8at% Ni were prepared. The feedstocks for each composition were warm-pressed and subsequently sintered in vacuum at 1150°C. Based on the XRD result, it clearly showed that the conventional sintering following warm-press method is promising in producing greater amount of the predominant NiTi (B2) phase and a minor fraction of martensitic NiTi (B19’) phase. The reversible phase transformation and the microstructure of the sintered samples have also been observed and discussed.

Abstract: Micro metal injection molding has become the promising method in powder metallurgy research in order to fabricate small-scale intricate parts in an influential process and competitive cost of mass production. Stainless steel 316 L powders with powder size of 150 nm and 5 μm were mixed with a binder with a water soluble component which consisted of a major fraction of water soluble Polyethylene Glycol (PEG), a minor fraction of polymethyl-methacrylate (PMMA) and some stearic acid has been used as a surfactant. This work aims to investigate the rheological properties of a feedstock which are efficiently characterised by capillary Rheometry to measure apparent viscosities at different temperatures and shear rates. Results obtained by the varying feedstock characteristics, when viscosity decreases by increasing of shear rate at certain temperature feedstock should have a pseudoplastic behaviour. Melt viscosity of the feedstock was decreased by adding nanoscale powders. The reduced (n) values at high temperature with addition of nanoparticles indicated a possible increase in the shear-thinning behavior.