Formation of Intermetallic Al2Pt-Phase by High Pressure Torsion of Elemental Chips at Cryogenic Temperature

The intermetallic compound Al₂Pt has potential of use in radiation sensing devices and selective solar absorbers, and is a promising protective coating of jet engine turbine blades. In our study, we demonstrate for the first time the possibility of forming nanocrystallites of the Al₂Pt intermetallic compound in an Al-Pt disc produced by high pressure torsion (HPT) of elemental chips at cryogenic temperature. The composition of the Al + Pt mixture corresponds to the Al₂Pt stoichiometry. Microhardness dependences against the distance from the disc center have been plotted and phase composition in the different points has been investigated. The formation of some high-strength phases was confirmed by a significant increase in microhardness near the edge of the cryodeformed Al-Pt disc. The Al₂Pt intermetallic phase and amorphous phase were revealed both in XRD-scans and TEM-observations. The spread of Al₂Pt crystallites sizes is wide and ranges from 10 to 200 nm. It was found that the amorphous phase had a composition of about 85Al-15Pt (at%). Although Pt is almost insoluble in Al in an equilibrium state, it was suggested that a non-equilibrium solid solution of Pt was formed in the Al matrix under cryo-HPT.