TiPt HTSMA produced by spark plasma sintering of elemental powders

摘要

Titanium-platinum (Ti_(50)Pt_(50)) alloy has been identified as a potential candidate for high temperature shape memory alloy (HTSMA) applications such as actuators in jet engines. This work evaluates powder metallurgy as an alternative processing route with the added benefit that near net shaped components can be formed. Spark plasma sintering (SPS) of blended elemental titanium and platinum powders was carried out. The sintering conditions used were: temperatures ranging from 1200 to 1400°C and sintering times ranging from 10 to 30 minutes. SEM with EDS, XRD and DSC were carried out to study the results. Results showed that SPS only achieved high density, but not homogenisation of the alloys. All sintering conditions resulted in formation of the martensitic TiPt phase of interest, together with some or all of the following phases: Ti, Ti_3Pt, Ti_4Pt_3, Ti_3Pt_5 and Pt. Post sintering annealing treatments were carried out to homoginise the alloys at 1300°C for times ranging from 5 to 15 hours. With sufficient annealing times a two phase microstructure was produced with TiPt as the majority matrix phase and Ti_3Pt_5 as the precipitate phase.