The effects of Ti and Cr additions on the phase equilibria and properties of (Pt)/Pt3Al alloys

Stabilizing the L12 structure of Pt3Al(r) in the Pt-Al-Sc system

“…Meiniger and Ellner, [25] Kamm and Milligan, [30] and Biggs et al [26] pointed out that small amounts of Ni stabilize the L1 2 structure of ␥Ј, just as Hill et al [9] found for Cr. The Nb, [23,24] Ti, and Ta [9,10] also showed potential to induce the L1 2 structure. On the other side, tetragonal modifications of Pt 3 Al(r) have been observed in Pt-Al alloys with additions of Ru [10] and Ir.…”

“…[16][17][18][19] At low temperatures, Pt 3 Al(r) undergoes a phase transformation. Mishima and co-workers [16,17] and Hill et al, [9] as well as Yamabe-Mitarai and Aoki, [22] deduced from XRD experiments that the low-temperature modification of Pt 3 Al(r) has the D0' c structure in the Strukturbericht designation. [31] Additionally, Mishima and co-workers [16,17] reported that Pt 3 Al(r) as well as Pt 3 Ga have D0 c structures at intermediate temperatures.…”

“…Appropriate alloying and heat treatment of these so-called refractory superalloys should lead to a fine distribution of a coherently embedded ␥Ј phase with L1 2 structure. [2][3][4][5][6][7][8][9][10][11][12][13][14] A major drawback of Ir and Rh alloys is their brittleness. [15] Hill and co-workers conducted an extensive assessment of systems with Pt as the major constituent.…”

“…by increasing Fe concentration, the L1 2 structure is stabilized. Hill et al [9,10] found that Cr, Ti, or Ta stabilizes the L1 2 form of Pt 3 Al(r) at low temperatures, whereas a tetragonal modification was observed at room temperature in Pt-Al alloys with additions of Ru and Ir. [10] Yamabe-Mitarai and Aoki [22] confirmed that Ir additions to Pt-Al alloys lead to tetragonal ␥Ј.…”

High Temperature Corrosion Resistance of Pt-Based Superalloys in 0.2% SO2-N2 Gas

“…A comprehensive discussion of these phase formations and their influence on the mechanical properties of Pt-based superalloys can be found in Cornish et al [24]. The high temperature precipitate form was stabilised by adding Cr, Ti and Ta [25]. The optimum alloy selected for this investigation was based on the quaternary alloy system (Pt-Al-Cr-Ru), and is a fine twophase mixture.…”