The Al−Pt (Aluminum-Platinum) system

Platinum-Based Alloys and Coatings: Materials for the Future?

“…The twin bands disappeared as the crystal structure changed during the phase transformation. As a check, the transformation was also observed in diffraction mode (because the diffraction patterns of the two phases are different), and confirmed that the phase diagram of Oya et al (1987) for the Pt-Al system is more accurate than that of McAlister and Kahan (1986) for these alloys. This was an important result, both because previous attempts to decide which was the most applicable phase diagram -McAlister & Kahan (1986) or Oya et al (1987) -using SEM, XRD and DTA had been unsuccessful, and because knowledge of the transformation temperatures is vital for application of the alloys.…”

“…At elevated temperatures, L1 2 -Pt 3 Al does not show an anomalous increase of the flow strength with increasing temperature as exhibited by L1 2 -Ni 3 Al (Takeuchi & Kuramoto, 1973), although Pt 3 Al should be stronger than Ni 3 Al at any temperature . In the Ni-Al system, Ni 3 Al has only one structure, whereas the Pt 3 Al phase has at least two (McAlister & Kahan, 1986) if not three (Oya et al, 1987) forms. There are two conflicting phase diagrams regarding the transformation temperatures of ' Pt 3 Al.…”

“…There are two conflicting phase diagrams regarding the transformation temperatures of ' Pt 3 Al. According to McAlister & Kahan (1986), there is a transformation of the high temperature Pt 3 Al phase from L1 2 to a tetragonal low temperature variant (designated D0'c) at ~1280°C. However, Oya et al (1987) showed an additional transformation at a lower temperature, with their transformations given as '' 1 at ~340°C and ' 1 ' 2 at 127°C.…”

“…Conversely, Ru and Ir stabilised a lower temperature modified D0 c type lath structure. This was recognised as originating from the displacive cubic ~Pt 3 Al  tetragonal ~Pt 3 Al reaction (McAlister & Kahan, 1986;Oya et al, 1987), since there were distinct bands (twins) in the precipitates (Douglas et al, 2001(Douglas et al, & 2007Santamarta et al, 2003;Douglas, 2004). These precipitates often had more complex appearances (Figure 6b), such as ogdoadically-diced shapes identified by Westbrook (1958).…”

Rhombohedral AlPt films formed by self-propagating, high temperature synthesis.

“…McAlister and Kahan have completed an extensive review of previous experiments (McAlister, 1986); a phase diagram from their work is shown in Figure 1. Although some questions remain regarding AlPt 2 and the low temperature form of AlPt 3 , the equilibrium phases of Al-Pt are well studied.…”