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In this study, two kinds of micrometre sized SiC powders (as received and ball milled) were used as the starting materials to investigate the effect of ceramic surface morphology on the coating characteristics. Determined optimised electroless deposition bath values of pH ( 9) and bath temperature (708C) were used. It was found that etching pretreatment was very effective on the coating quality for both types of SiC powders. The experimental results indicated that milling of the powders led to the formation of multimodal sized ceramic powders with sharp edges and rough surfaces, which resulted in a uniform adhesive metallic layer on the powders without any crack formation. Finally, the effect of cobalt coating on the incorporation of ceramic particles into the molten aluminium during fabrication of aluminium matrix composite was studied, and it was revealed that a significant improvement in incorporation could be obtained using cobalt coated ceramic particles.

Creep behavior of the eutectic Sn-9Zn, Sn-9Zn-0.5Ag, and Sn-9Zn-0.5Al solder alloys was studied by impression testing under constant punching stress in the range of 60 MPa to 130 MPa and at temperatures in the range of 298 K to 370 K. Analysis of the data showed that, for all loads and temperatures, Sn-9Zn-0.5Al had the lowest creep rates and thus the highest creep resistance among all materials tested. The creep resistance of Sn-9Zn-0.5Ag was slightly lower than that of the Al-containing alloy. The enhanced creep behaviors of the ternary alloys are attributed to the presence of AgZn 3 and very fine Zn particles, which act as the main strengthening agents in the Sn-9Zn-0.5Ag and Sn-9Zn-0.5Al alloys, respectively. Assuming a power-law relationship between the impression rate and stress, average stress exponents of 6.9, 7.1, and 7.2 and activation energies of 42.1 kJ mol -1 , 42.9 kJ mol -1 , and 43.0 kJ mol -1 were obtained for Sn-9Zn, Sn-9Zn-0.5Ag and Sn-9Zn-0.5Al, respectively. These activation energies are close to 46 kJ mol -1 for dislocation climb, assisted by vacancy diffusion through dislocation cores in the Sn. This, together with the stress exponents of about 7, suggests that the operative creep mechanism is dislocation climb controlled by dislocation pipe diffusion.

The influence of isothermal aging on the creep behaviour of Sn–9Zn and Sn–8Zn–3Bi solder alloys was studied by impression testing. The tests were carried out under constant impression stress in the range from 90 to 230 MPa at room temperature. Aging affected the microstructure and, thus, the creep behaviour of the materials. The binary Sn–9Zn alloy, with an as cast microstructure characterised by an almost uniform distribution of fine Zn precipitates, was much more creep resistant than the aged condition containing a more sparse precipitate in a softer matrix. In the ternary Sn–8Zn–3Bi alloy, however, isothermal aging enhanced Bi precipitation with almost no change in the distribution and density of Zn particles, the result being an improved creep resistance of the aged material. Irrespective of the processing condition, Sn–8Zn–3Bi showed much lower steady state creep rates than the Sn–9Zn due to both precipitation and a solid solutioning effect of Bi in the Sn matrix. The stress exponents of the as cast and aged conditions were found to be respectively 8·5 and 7·7 for Sn–9Zn and 9·8 and 7·8 for Sn–8Zn–3Bi. These values are in agreement with those determined by room temperature conventional creep testing of the same materials reported in the literature.