| Title |
The Effect of Point Defects on the Precipitation of Fe in NiAlFe Intermetallic Compounds |
| Authors |
박희섭(Hee Sub Park) ; 고홍석(Hong Seok Ko) ; 홍경태(Kyung Tae Hong) ; 이경섭(Kyung Sub Lee) |
| Abstract |
The influence of point defects on the precipitation was investigated in NiAlFe by means of magnetic susceptibility measurement, differential scanning calorimetry, microhardness and TEM analysis. The magnetic measurements revealed that the ferromagnetic phases consisting of Fe atoms precipitated rapidly at about 700K and dissolved completely at temperatures over 1000K in NiAl alloys containing Fe over 6 at.%. Formation energy of thermal vacancies in NiAlFe was determined to be about 0.85 eV through analysis of quenching data in the range of 1000K-1500K. TEM analysis indicated that very fine α-Fe particles were distributed uniformly in NiAl matrix. Superparamagnetic behaviors were attributed to Fe particles in NiAl12Fe. Only the stoichiometric NiAl containing Fe showed a significant increase in magnetic susceptibility during aging treatment. It is considered that she formation of Fe particles is not dependent on consitutional vacancy but thermal vacancy. |