An Atom Probe Field Ion Microscope Study of Model Ni-Al Superalloys Containing Be

Abstract
Atom probe field ion microscopy and transmission electron microscopy have been used to characterise the phases present, and their compositions, in four model Ni-Al superalloys containing Be. In agreement with the limited information available on phase stability within the ternary Ni-Al-Be system, atom probe results indicated that these alloys were in the three phase, γ-Ni, γ-Ni₃Al and β-NiBe, region of the ternary diagram. Beryllium was found to substitute on the 'Al' sites within the γ, consistent with previous results from Be-doped NiAl. The experimental results have shown that the Be additions have resulted in the precipitation of phases enriched in Be within the γ phase. The morphology of the phases enriched in Be ranged from monatomically thick plates to lenticular precipitates. Hardness measurements indicate significant hardening resulting from the addition of Be to model Ni-Al alloys.