Influence of <FONT FACE=Symbol>g</font>-phase on the high- temperature oxidation of NiAl-Fe alloys

• Main Authors: Maurício de Jesus Monteiro, Fernando Rizzo Assunção, Zeng Chaoliu
• Format: Article
• Language: English
• Published: Associação Brasileira de Metalurgia e Materiais (ABM); Associação Brasileira de Cerâmica (ABC); Associação Brasileira de Polímeros (ABPol) 1999-07-01
• Series: Materials Research
• Subjects: intermetallic compounds; NiAl; Fe; oxidation
• Online Access: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1516-14391999000300011

The oxidation of NiAl, NiAl-20at.%Fe and NiAl-30at.%Fe at 1000-1100 °C in air has been studied. Pure NiAl shows excellent oxidation resistance due to the formation of an Al2O3 layer. NiAl-20Fe also shows good oxidation resistance due to the formation of an Al2O3 scale on a <FONT FACE="Symbol">b</font>-phase substrate. Moreover, some nodules consisting of mixed oxides of Fe and Ni grow over the ductile <FONT FACE="Symbol">g</font>-phase surface incorporated to the <FONT FACE="Symbol">b</font>-phase substrate. NiAl-30Fe alloy undergoes a much faster oxidation due to the formation of a non-protective Fe and Ni-rich scale, which is extremely susceptible to spallation. The addition of Fe to NiAl is detrimental to its oxidation resistance.