Thermal aspects are becoming increasingly important for the reliability of the electronic components due to the continuous progress of the electronic industries. Therefore, the effective thermal management is a key issue for packaging of high performance semiconductors. The ideal material working as heat sink and heat spreader should have a CTE of (4-8) × 10 −6 K −1 and a high thermal conductivity. Metal matrix composites offer the possibility to tailor the properties of a metal by adding an appropriate reinforcement phase and to meet the demands in thermal management.Copper/SiC and copper/diamond composites have been produced by powder metallurgy. The major challenge in development of Cu/SiC is the control of the interfacial interactions. Silicon carbide is not stable in copper at the temperature needed for the fabrication of Cu/SiC. It is known that the bonding between diamond and copper is very weak in the Cu/diamond composite. Improvements in bonding strength and thermo-physical properties of the composites have been achieved by • a vapour deposited molybdenum coating on SiC powders to control interface reactions, • using atomized Cu(X) alloys with minor additions of carbide formers, e.g. X = Cr, B, to improve the interfacial bonding in Cu-diamond composites.

Electrochemical impedance spectroscopy has been used to study the electrochemical behaviour of ternary Mg 60 Ti 10 Si 30 and Mg 88 Ti 5 Si 7 alloy samples fabricated by mechanical alloying of the elemental powders in an argon atmosphere. The influence of different milling times up to 25 h and heat treatment on the electrochemical behaviour of the samples, after compacting under pressure into disks, has been investigated in 0.1 M Na 2 SO 4 and 0.01 M NaCl electrolyte solutions. Complementary measurements of open circuit potential, polarisation curves, and surface and microstructural analysis have been carried out. The experimental results revealed that corrosion is greater for Mg 88 Ti 5 Si 7 which contains free magnesium; however, in sulphate solution a protective oxide layer formed can reduce the corrosion rate. In Mg 60 Ti 10 Si 30 , heat treatment increases corrosion, which is explained through a greater tendency for pitting corrosion. Comparison is made between the electrochemical impedance data and the nanophase structure as well as with the electrochemical behaviour of other magnesium alloys.

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The influence of silver on the structure and mechanical properties of sputter-deposited Ti-ALAg films with an aluminium content close to 48 at.% and 0 < at.% Ag < 3 was investigated. A new tensile test procedure has been developed to evaluate the ductiLity of the films. The results show that the as-deposited films are metastable formed, essentially, by an extended c-u-Ti solid solution. Annealing at 6OO'C gives rise to the formation of y-TN intermetallic compound. Silver does not lead to structural modifications of the TiAl system nor influences significantly its ductility. However, a hardness increase of the as-deposited fihns with silver contents up 10 1.6 at.% is observed. (C 1999 Elsevier Science S.A. All rights reserved.Rewords:

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