Vashchuk D. Structure and properties of plastically deformed Invar Fe-Ni-C alloys

The effect of the plastic deformation by hydroextrusion (HE e = 0.45 - 3.47) and HE in combination with drawing (e = 4.69) or high pressure (2 GPa) on structure and properties of standard Invar f.c.c. alloy Fe-35%Ni-0,49%Mn (0,03%C) and the deformation by upsetting on the structure-phase state of the alloy Fe-35%Ni-0,49%Mn (0.03% C) and the alloy Fe-30,9%Ni-1,23%C with high carbon content was studied in this work. Treatment of the alloys by various methods was performed on equipment of the Donetsk O.O. Galkin Institute for Physics and Engineering, N.A.S. of Ukraine. The study was performed using X-ray diffraction techniques, electron microscopy, magnetometry, dilatometry, Mossbauer spectroscopy, internal friction, ultrasonic method and durometry. It was established that HE and upsetting cause non-monotonic change of TEC of the Invar Fe-Ni-Mn and Fe-Ni-C alloys depending on the strain, which is the result of the effect of a formed structural stressed state on magnetostrictive and Gruneisen contributions in thermal expansion as a result of changes in stiffness of interatomic interaction and exchange interspin interaction. The work shows the efficiency of hydroextrusion and upsetting for strengthening of Invar alloys Fe-35%Ni-0,49%Mn and Fe-30,9%Ni-1,23%C while saving Invar properties in practically important temperature range 200 - 370 K.