Nur Azmah Nordin

Refinement of Mg2Si Particulate Reinforced Al-20%Mg2Si In Situ Composite with Addition of Antimony

Al-Mg2Si in-situ composite have received wider attention due to their improved properties which mark them as attractive candidate to manufacture most of automotive and aerospace components. Result show that the melt treatment of the in-situ composite by addition of antimony caused to refining the morphology of primary Mg2Si reinforcement which would expect to improve the mechanical properties. Effect of Sb on the characteristics parameters of Mg2Si particles have been investigated by thermal and microstructural analysis. The result has revealed that addition of 0.8 wt.% Sb produced optimum refinement effect on the morphology as coarse structure has been changed to polygon one. The result also showed depression with nucleation temperature, TN and growth temperature, TG which also correspond to the refinement effect.

Evaluation of the effect of bismuth on Mg2Si particulate reinforced in Al-20%Mg2Si in-situ composite

Al-Mg2Si in-situ composite as a class of advanced engineering materials has possessed better properties which enhanced them to be potential candidate to manufacture most of automotive and aerospace components. Melt treatment of the in-situ composite by addition of bismuth, Bi has resulted in a change of primary Mg2Si reinforcement to a refined morphology which would expect to improve mechanical properties of the composite. Characteristics parameters of Mg2Si particles have been investigated via thermal and microstructural analysis. It has revealed that 0.4wt.% Bi addition produced optimum refinement effect on the morphology since coarse structure has been change to polygon one and reduced most in size. The result also showed depression in nucleation temperature, TN and growth temperature, TG which also correspond to the refinement effect.

Preliminary Study on Deformation and Recrystallization Behavior of Pure Tin for Mitigation of Whisker Growth

Since the mechanism of Sn-whisker growth is closely related with the behavior of deformation and recrystallization, understanding of the behavior is very important to establish the measure for mitigation of whisker growth. In this work, microstructural changes after heavy deformation by scratching were characterized by EBSD for a single crystal of β-Sn, and the following results were obtained. Three types of crystal grains appear immediately after the deformation; small grains in aggregation, large serrated grains and rim-grains. The small grains are considered to be formed by dynamic recrystallization. They continue to grow at a room temperature over a lengthy period of time. The large grain has a certain crystallographic relationship with the matrix where <100> axes of the large grain and the matrix are almost parallel to each other. The serrated boundaries of large grain are so stable that the large grain does not show a grain growth process. The stable boundary is considered to promote a continuous growth of whiskers.

The Changed of Behaviour of MR Fluid in MR Damper after a Long-Term Operation

Magnetorheological (MR) fluid devices are now applied in various applications. Although a lot of studies have been discussed in long-term implementation of MR devices, only few studies have concerned on MR fluid application in valve operation mode, such as at MR valve. The experiments were conducted on a dynamic test machine in a custom MR damper with meandering MR valve. The experiment test was applied at continuous-load in long term-operation with parameters of 20 mm length of stroke, 0.4 Hz of frequency, 0.5 A of applied current and 175,000 cycles. The rheological properties of MR fluid were characterized using rotational and oscillatory shear rheometer. The result showed that the rheological properties of MR fluid changed after applied in long-term operation. The changed of MR fluid also investigated through morphological characteristics using SEM and EDX.

Magnetorheological Elastomer Silicone-Based Containing Corroded Carbonyl Iron Particles

In this study, magnetorheological elastomers (MREs) were synthesized using silicone rubber (SR) as the matrix element interspersed with 70 weight percent of corroded carbonyl iron particles (CIPs). The CIPs were corroded in dilute hydrochloric acid (HCl) for 4 hours. The rheological properties related to MR effect were experimentally examined in the absence and presence of magnetic field at various current using a rheometer. The experimental results depicted the MR effect of the MRE with corroded CIPs decreased one-half, 27% as compared to the non-corroded samples, 58%. The correlation between the purity of CIPs and storage modulus of MR elastomer is examined in this study.

Characterization of Phase Formation in Al-20%Mg2Si-2%Cu Metal Matrix Composite

Advantage of Al-Mg2Si metal matrix composite (MMC) is due to the particulate reinforced Mg2Si in the Al matrix that has improved mechanical properties of the in situ composite. In particular, the composite has been chosen as the structural material for automotive and aerospace components. The hypereutectic Al-Mg2Si composite should be comprised of two morphologies, namely primary Mg2Si and pseudo-eutectic Al-Mg2Si phase. However, as-received commercial Al-20Mg2Si-2Cu in situ composite contained a wide range of elements that affect the resultant microstructure of the in situ composite. In fact, four different morphologies have been identified in the in situ composites. The first phase is dark facet primary Mg2Si particles, surrounded by pseudo-eutectic Al-Mg2Si phase in lamellar structure. Along the eutectic boundary is the formation of needle-like Al5FeSi intermetallic and the phase is surrounded by Al5Mg8Si6Cu2+Al2Cu as last phase nucleated. Optical micrograph, SEM imaging, EDX analysis and elemental mapping have revealed these phases correspond to shape of morphologies and respective molecular compound.