An austenitic alloy based on nickel, chromium and iron, and having a high aluminum content, intended for use at a given operating temperature (Ts) between 900° C. and 1200° C., the alloy comprising 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 hafnium, between 0.002% and 0.1%, silicon between 0 and 0.5%, manganese between 0 and 0.5%, tungsten between 0 and 2%, and iron as the balance of the elements in the alloy. 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).