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The objective of this program is to design and characterize new, improved high-temperature materials based on boron-doped Ni3Al + Fe for structural use in advanced coal conversion systems. Chromium is a key alloying element that improves resistance to oxidation, corrosion, and environmental embrittlement in nickel-iron aluminides by promoting the rapid formation of protective oxide scales. Alloying with 3 to 7 at. % Cr dramatically reduces dynamic embrittlement in oxidizing environments at 400 to 800°C. Chromium and iron additions increase the stability of the ordered body-centered cubic phase that is brittle at room temperature and weak at elevated temperatures. The formation of the B2 phase in the aluminides leads to lowering the tensile ductility at lower temperatures and the strength at higher temperatures. This study of alloying effects has led to the development of an aluminide with the composition: Ni-18.5 ± 0.5% Al-10.5 ± 0.5% Fe-7 ± 0.5% Cr-0.2% Zr- 0.7% Mo-0.1% B (at. %). Corrosion studies have demonstrated that chromium additions of 7 at. % or greater were very effective in minimizing the sulfur attack on nickel-iron aluminides. Sulfidation protection can also be afforded by oxide films produced in air; however, the oxidation temperature should be 1000 to 1050 degree Celsius, and the alloys must contain 3 at. % or greater chromium. The nickel-iron aluminides developed were weldable using both the electron beam and gas tungsten arc processes.