INCONEL MA 6000 combines precipitation strengthening (gamma prime, γ´, precipitates) from its Al, Ti, and Ta content for intermediate temperature strength with oxide dispersion strengthening from the Y2O3 addition for strength and stability at very high temperatures. It contains about 25% of γ´ precipitates.
The dispersoid dimensions are 30 nm average diameter and 0.1 µm average spacing. As in MA 754, the Y2O3 reacts with oxygen and aluminum to form uniform dispersions of yttrium aluminates, e.g., yttrium-aluminum garnet 5Al2O3·3Y2O3 (YAG). The YAG dispersoid appears to be very stable.
Negligible coarsening is observed for stress rupture tests at ~750°C and only small coarsening for temperatures of 950 to 980°C at rupture lives beyond 104 hours. These changes cause no serious loss in the loadbearing capability of the alloy, for practical applications.[7] Figure 2.3 shows the 1000-hour creep rupture strength for MA 6000 alloy compared with several other MA ODS alloys.[8] It is clear that MA 6000 has superior rupture strength at the highest temperatures (less than 900°C) and comparable strength to MAR-M 200 at intermediate temperatures. MA 6000 alloy has been used to a small extent, so far, in gas turbine engine blades.