Abstract: heinternalfriction at400 850 ℃in a high pure Fe Nb Calloy hasbeen measured, and a largestress dependent magnetomechanicalhysteresisdamping peakof whichthe peaktempera turevariesfrom 666 to740℃asstrain amplitudechanges wasdiscovered. Theconditionsof the peak appearing and disappearing,somecharactersofthepeakandtheeffectofsomefac torsuch asascending and descending temperature, frequency, amplitude, deformation andannealing etconthe peak havealso beenstudied. The method to determinetheinternalstress σstand σi obstructing Barkhausen jumps of domains by internal friction experiences and the physical mechanism producingthe magnetomechanicalhysteresisdamping temperature( Qm 1 T) peakinthealloy were proposed.

Key words: internalfriction, Fe Nb Calloy