The samples of Fe77.95Mn20Si2C0.05 alloy were quenched in water (from T=950⁰C) and were subjected to explosive treatment, created by explosive missile device evolving the pressure pulse ~45 GPa during 1 s. The extremely energy densities, high pressures, shear stresses at explosive treatment could initiate the various chemical reactions or phase transitions. Magnetometry methods allowing to fix and to run down even insignificant concentration changes of α -phase were used.
The initial samples without explosive treatment contain 0.7% α -phase after quenching according to hysteresis dependence of magnetization on magnetic field strength (H). The crystallites' size was estimated as about 300 nm according to coercitivity force. After explosive treatment (P=45 GPa) the ferromagnetic component in the sample becomes the smaller and with respect to magnetization corresponds to 0.2% α -phase content with crystallites' size about 150 nm. The temperature investigations with heating of samples up to 460⁰C result in weak decreasing of magnetization for both samples. Further heating up to T=600⁰C offered to determine of the Curie temperature (which runs 650⁰C of observed phase for both samples possible. And that was typical for α -phase.
Thus under missile explosive treatment α -phase content reduces one-third as large for Fe77.95Mn20Si2C0.05 steel with decreases of crystallites sizes. Probably this was stipulated by α -> γ inverse transformation initiated by high pressure and shear stresses.