Development of metal matrix composites by direct energy deposition of ‘satellited’ powders

Abstract

Limited research has been undertaken investigating the material design freedoms that are granted through the use of additive manufacturing methods, especially in the development of materials specifically formulated for additive processes. In this study, a new material combination was evaluated for use with directed energy deposition methods of additive manufacturing. Here, a Ti-6Al-4 V powder is processed in combination with a much finer titanium diboride powder following a satelliting procedure. The resulting combination consists of large Ti-6Al-4 V particles encased in finer titanium diboride. Deposited composites presented exhibit TiB needles associated with increased hardness. Processing conditions were detailed which permit the deposition of the prepared feedstock onto Ti-6Al-4 V substrates. Microstructural characterisation revealed that the composite was made up of eutectic TiB precipitates dispersed in α-β Ti matrix with few partially melted Ti-6Al-4 V and TiB2 particles. Satelliting TiB2 powder onto Ti-6Al-4 V particle surfaces has significantly improved the homogeneity of composite which is characterised with randomly oriented and uniform distribution of TiB needles in the microstructure. Hardness of composites ranged between 440–480 HV. Hence, the feedstock preparation method proposed has been found to be effective and can be adapted for low cost and rapid formulation of a host of materials for processing by additive manufacture.