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

• Alternative approach of alloying titanium powders by electroless plating process
• Alkaline electroless bath is better than acidic bath for powder compactibility.
• A novel approach by integrating mathematical models explains compaction behaviour.
• Contributions of particle related individual mechanisms during compaction process

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 Alderborn 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.

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