Austenitic alloy with high aluminum content and associated design process

A method of forming an austenitic alloy based on nickel, chromium and iron, and having a high aluminum content, for use at a given operating temperature (Ts) between 900° C. and 1200° C., and comprising alloying the following elements, in weight percent:

• chromium between 20% and 32%,
• nickel between 30% and 60%,
• aluminum between 3.5% and 6%,
• carbon between 0.4% and 0.7%,
• titanium between 0.05% and 0.3%,
• niobium and/or tantalum between 0.6 and 2%,
• an element, composed of at least one rare earth and/or of hafnium, between 0.002% and 0.1%,
• silicon between 0 and 0.5%,
• manganese between 0 and 0.5%,
• tungsten between 0 and 2%,
• iron to balance the elements in the alloy;
• the method comprising selecting the respective weight percentages of aluminum XAl, nickel xNi, chromium xCr, titanium xTi, carbon xC, niobium xNb, tantalum XTa, silicon xSi and manganese xMn, so that the alloy has less than 1% by volume of an intermetallic B2-NiAl phase and less than 1% by volume of an alpha prime phase rich in chromium, after subjecting the alloy to an operating temperature (Ts).