INCOLOY® alloy 907 (UNS N19907) is a nickel-ironcobalt alloy having high strength along with a low coefficient of thermal expansion. The alloy is strengthened by age-hardening heat treatments. Table 1 lists the chemical composition of the alloy. The combination of low expansion and high strength makes INCOLOY alloy 907 useful for gasturbine components. The low expansion enables closer control of clearances and tolerances for greater fuel efficiency. The high strength makes possible higher strength-to-density ratios for lower weight in aircraft engines. For those reasons, INCOLOY alloy 907 is used for gas-turbine seals, shafts, casings, and other structural parts. The properties of INCOLOY alloy 907 are attractive for other applications including instrumentation, glass-to-metal sealing, ceramicmolding dies, and electricity generation. Table 1 - Limiting Chemical Composition, % Nickel ..........................................................................35.0-40.0 Cobalt..........................................................................12.0-16.0 Iron ...............................................................................Balance* Niobium...........................................................................4.3-5.2 Titanium...........................................................................1.3-1.8 Aluminum......................................................................0.2 max. Silicon..........................................................................0.07-0.35 Table 2 - Physical & Thermal Properties Density, lb/in3 .....................................................................0.301 Mg/cm3 ...................................................................8.33 Melting Range, °F .....................................................2440-2550 °C .....................................................1335-1400 Specific Heat, Btu/lb-°F ....................................................0.103 J/kg-°C.......................................................431 Curie Temperature, °F ...................................................750-850 °C ..................................................400-455 Thermal Conductivity at 200°F (93°C), Btu-in/ft²-h-°F............................................108.5 W/m- °C ......................................................15.6 Electrical Resistivity, ohm circ mil/ft.....................................419 µΩ-m .........................................................0.697 Young’s Modulus, 103 ksi ....................................................23.9 GPa...............................................................165 Shear Modulus, 103 ksi .........................................................8.8 GPa.................................................................61 Poisson’s Ratio....................................................................0.36 Physical Properties Some physical properties of INCOLOY® alloy 907 are listed in Table 2. The values were determined for agehardened material. Values for modulus of elasticity were determined dynamically and were used to calculate Poisson’s ratio. Values were determined at room temperature unless otherwise noted. The composition of INCOLOY alloy 907 is designed to provide a low coefficient of thermal expansion that remains constant over a broad temperature range. As shown in Figure 1, coefficient of expansion is typically 4.0 to 4.5 x 10-6/°F (7.2 to 8.1 x 10-6/°C) at temperatures to about 800°F (430°C). The expansion rate is about half that of other alloys of comparable strength. Further, the expansion characteristics of alloy 907 are highly reproducible after both static and cyclic exposure to temperature. INCOLOY alloy 907 has a nearly constant modulus of elasticity over temperature ranges from the cryogenic region to 1200°F (650°C). Table 3 lists modulus values at various temperatures. Testing was done on agehardened material using a dynamic method. The combination of low expansion and constant modulus makes INCOLOY alloy 907 highly resistant to thermal fatigue and thermal shock. The alloy’s hightemperature performance is also enhanced by relatively high thermal conductivity. °C Poisson’s Ratio °FTemperature Table 3 - Modulus of Elasticity of Age-Hardeneda  INCOLOY alloy 907 a Age hardened for rupture-limited applications 70 200 400 600 700 800 900 1000 1200  1400 1600  21  93 204 316 371 427 482 538 649 760 871 23.9 23.8 23.8 24.0 24.1 24.3 24.2 23.9 23.0 21.8 20.5 165 164 164 165 166 168 167 165 159 150 141 8.8 8.7 8.7 8.9 9.0 9.1 9.0 8.8 8.4 8.0 7.4 61 60 60 61 62 63 62 61 58 55 51 0.36 0.37 0.37 0.35 0.34 0.34 0.34 0.36 0.36 0.36 0.39 Young’s Modulus Shear Modulus 10 GPa 3 ksi 10 GPa 3 ksi *Reference to the ‘balance’ of an alloy’s composition does not guarantee this is exclusively of the element mentioned, but that it predominates and others are present only in minimal quantities.