Modelling compaction behaviour of nickel-phosphorus and nickel-boron electroless coated titanium powders

Electroless plating is used as an alternative approach to alloying the commercially pure titanium powders. Two types of irregularly shaped powders, which differ in particle size distribution, are coated with nickel-phosphorus (Ni-P) and nickel-boron (Ni-B). A novel method, combining aspects of the Kawakita and Alderbom approaches, has been employed in order to understand compaction behaviour. The overall consolidation is described by a Kawakita-Ludde relationship, and the transition pressures which demarcate the limits of rearrangement only and plastic deformation only are identified using a modification of the Alderborn relationship. A significant increase in green strength is achieved with the Ni-B coated powders, and this is attributed to a modification of friction conditions and the number of possible contacts, which lead to an increased contribution from plastic deformation. The Mohr-Coulomb model and Ohyane equations are used to describe the contribution of the number of contacts on green strength. (C) 2015 Elsevier B.V. All rights reserved

The influence of Mg-Zr master alloy microstructure on the corrosion of Mg

In this study, sixteen Mg-Zr alloys were produced to investigate the role of Zr on corrosion of Mg. Alloys were produced using two different commercial Mg-Zr master alloys commonly used for grain refining Mg, but which contain different Zr particle size distributions. It is seen that the master alloy with a smaller Zr particle size leads to an alloy containing more Zr in solid solution. The ratio of Zr in solid solution and in particle form was observed to have a marked effect on the corrosion of Mg