Emee Marina Salleh

Characterization of Tantalum Carbide Reinforced Copper Composite Developed Using Mechanical Alloying

The effects of the consolidation pressure on the properties of novel Cu-15vol% TaC composite was investigated. The copper-based composite has been prepared using a high energy planetary mill via in-situ route. A mixture of copper, tantalum and graphite powder was mechanically alloyed for milling time of 8 hours at speed of 400 rpm. The as-milled powder was consolidated by cold pressing under various pressure (i.e. 100, 200, 300 and 400 MPa) at room temperature and sintered in argon atmosphere at 900 °C for an hour. TaC phase was formed in copper matrix after sintering process. An increase in consolidation pressure resulted in an increase in hardness, electrical conductivity and density of the composites. The changes of bulk properties of the in-situ Cu-TaC composite were correlated to the formation of TaC phase and a reduction of porosity which led to an increasing in densification.

Synthesis of biodegradable Mg-Zn alloy using mechanical alloying: Effect of ball to powder weight ratio

The aim of this work was to study the effect of ball to powder weight ratio (BPR) on biodegradable binary magnesium-zinc (Mg-Zn) alloy synthesized using mechanical alloying. A powder mixture of Mg-5wt%Zn was milled in a planetary mill under argon atmosphere using a stainless steel container and balls. Milling process was carried out at 200 rpm for 5 hours using various BPR (i.e. 5:1, 10:1, 15:1, 20:1). Then, as milled powder was compacted under 400 MPa and sintered in a tube furnace at 300 °C in argon flow for an hour. The sintered density and microhardness of the alloy increased as BPR increased up to 15:1. However a further increasing showed a reduction in both density and microhardness which due to enlargement of crystallite and particle which resulted from the excessive internal energy during mechanical alloying.

Design of experiment (DOE) study of biodegradable magnesium alloy synthesized by mechanical alloying using fractional factorial design

The biodegradable nature of magnesium (Mg) makes it a most highlighted and attractive to be used as implant materials. However, rapid corrosion rate of Mg alloys especially in electrolytic aqueous environment limits its performance. In this study, Mg alloy was mechanically milled by incorporating manganese (Mn) as alloying element. An attempt was made to study both effect of mechanical alloying and subsequent consolidation processes on the bulk properties of Mg-Mn alloys. 2k−2 factorial design was employed to determine the significant factors in producing Mg alloy which has properties closes to that of human bones. The design considered six factors (i.e. milling time, milling speed, weight percentage of Mn, compaction pressure, sintering temperature and sintering time). Density and hardness were chosen as the responses for assessing the most significant parameters that affected the bulk properties of Mg-Mn alloys. The experimental variables were evaluated using ANOVA and regression model. The main paramet...