Heat treatments of the low-expansion superalloy Incoloy 909 for application in ceramic/metal joints and in metal matrix composites

Hot Isostatic Pressing

“…Methods for ceramic/metal joints in structures used at elevated temperatures must deal with two major restrictions, namely high residual stresses and excessive reaction zones that occur in the bonded region during joining and use; see reviews by Elssner andPetzow (1990), Pejryd (1992), Nicholas (1991), or Suganuma (1990). A third restriction, which according to Pejryd (1992) and R. Larker (1992 b) has received very limited attention, is the necessity to retain the optimum microstructure of the metal alloy after the heat treatments experienced during joining. These three restrictions are, more or less, influenced by both the selection of the joining method itself and of its associated parameters (such as temperature, time, pressure and chemical environment).…”

“…Due to the interest of using Incoloy 909 in two areas, namely in joints to Si 3 N 4 or SiC, and as a matrix with W or SiC fibers in metal matrix composites (MMC), a study by R. Larker et al (1992 a) has addressed this topic. Samples of "as-received" Incoloy 909 were heat-treated at five selected temperatures: 800 °C, 900 °C or 1000 °C for joining, and 1060 °C or 1150°C relevant for MMC purposes.…”

Microstructure characterisation of solution treated (ST) and solution treated and aged (STA) Incoloy 909

“…A gamma prime (c9) type phase forms in the alloy imparting age hardening based on a (Ni 3 ,TiNb) phase. [4][5][6][7] A further addition of Si at around 0?4 wt-% helped in reducing the SAGBO effect and aids tensile properties as well as assisting in reducing processing problems seen by the other two alloys. 4 One manifestation of the effect of adding Si is the formation of an A 2 B Laves phase during processing.…”

“…In alloy 909, however, the presence of the Laves phase assists during thermomechanical processing to improve grain control via restricting grain growth. [7][8][9][10][11] Several investigations are present in the literature on the ageing and overaging characteristics of alloy 909. [4][5][6][7][12][13][14] The recommended aging heat treatment for the alloy by Special Metals Co. is heat and hold at 718uC for 8 h, furnace cool to 621uC for 8 h, air cool.…”

“…[7][8][9][10][11] Several investigations are present in the literature on the ageing and overaging characteristics of alloy 909. [4][5][6][7][12][13][14] The recommended aging heat treatment for the alloy by Special Metals Co. is heat and hold at 718uC for 8 h, furnace cool to 621uC for 8 h, air cool. Heck et al 4 solution treated alloy 909 at 1038uC, followed by aging in 56uC increments from 538 to 1038uC for 0?1, 1?0, 10, 100 and 1000 h. The major strengthening phase (c9) precipitated in the temperature range 538-760uC, with an e0 phase [distorted hexagonal, (NiFeCo) 3 NbTi] precipitating from 700 to 950uC.…”