The temperature dependence of mechanical properties of iron near the temperature range of the alpha-gamma transformation has been studied. Beyond the temperature range of the transformation, the mechanical properties change monotonically with temperature; the alpha phase demonstrates a lower strength and a higher plasticity than the gamma phase. The maximum plasticity has been observed near the temperature of they gamma -> alpha a transformation during tensile tests. Increased plasticity in the range of the alpha-gamma transformation has also been observed in the dilatometric investigation under the conditions of uniaxial compression.

The martensitic transformation at 77 K has been experimentally studied in Fe-Ni-Mn alloys with isothermal martensitic transformations. Deformation at a temperature lower than the finish temperature of the spontaneous transformation results in an intense transformation accompanied by an increase in plasticity. The amount of martensite formed upon low-temperature deformation increases with decreasing manganese content in the alloy. Factors that determine the intensity of the martensitic transformation and the properties of the alloys in the course of low-temperature deformation are discussed.

The Fe100-xMnx alloys with an Mn content x = 6-30 at % obtained by mechanical alloying (MA) were investigated by X-ray diffraction and magnetic methods. It was established that MA results in a widening of the concentration interval of existence of the bcc (alpha) phase. Annealing of MA alloys leads to an increase in the stability of the gamma phase against the transformation into the alpha phase upon cooling. In the alloys with x less than or equal to 9 at %, a gamma --> alpha isothermal martensitic transformation was found at room temperature. The hexagonal close-packed E phase has not been observed in the alloys obtained by MA and after annealing. Room-temperature deformation of the gamma phase formed as a result of annealing leads to its transformation into the alpha and epsilon phases. The peculiarities of transformations of alloys obtained by MA are related to the low temperature of formation of the alloys upon MA and the high degree of their strain hardening.

The paper suggests a unified approach for the interpretation of the different kinetic types (athermal martensitic, isothermal martensitic, bainitic, normal) of polymorphic transformations based on the analysis of experimental data obtained at normal and high pressures.

Fe100-xMnx (6 less than or equal to x less than or equal to 30) and Fe100-xNiy (20 less than or equal to y less than or equal to 26) alloys (x and y given as at%) were prepared by mechanical alloying of elemental powders in a high-energy planetary ball mill. X-ray diffractometry and Mossbauer spectroscopy were used to determine structure and phase constitution of the samples. Thermo-magnetic measurements were used to determine the phase transformation temperatures. Mechanical alloying led to the formation of bcc alpha-Fe and fcc gamma-Fe based solid solutions with a high concentration of defects and fine crystallite size (10-20 nm). In the case of Fe100-xMnx samples, only the bcc phase was observed with x less than or equal to 6, while both bcc and fcc phases were present with 8 less than or equal to x less than or equal to 30. For the Fe100-yNiy system the single bcc phase was observed with y less than or equal to 20 and the two phases with 22 less than or equal to y less than or equal to 26. Only the fcc phase was observed after annealing and cooling to room temperature: for x greater than or equal to 10 in Fe100-xMnx, and for y greater than or equal to 22 in Fe100-yNiy samples. By cooling down to 77 K annealed samples of those compositions the Fe-Mn austenite resulted to be stable, whereas the Fe-Ni austenite partially transformed into martensite. Isothermal gamma --> alpha martensitic transformation was observed in Fe100-xMnx alloys for x greater than or equal to 9 at room temperature. The final phase constitution significantly depended on the annealing temperature. Partial transformation of austenite phase into bcc and/or hcp martensite could be also obtained by slight deformation.

The martensitic transformation (MT) under tensile deformation at 77K in a series of Fe-Ni-Mn alloys was studied. The amount of martensite formed during the tensile test depends on the applied stress and on the Mn content which determines the martensitic point and the MT start stress. Elongation of the tensile tested samples has a maximum value in the alloys containing the 50% amount of martensite formed during the tensile test. Parameters which determine the intensity of the MT and plasticity of the samples under loading are discussed.

physica status solidi (a)Volume 105, Issue 1 p. K29-K32 Short Note Amorphisation of gallium antimonide under the conditions of shear deformation under pressure M. M. Aleksandrova, M. M. Aleksandrova Institute of High Pressure Physics, Academy of Sciences of the USSR, Troitsk Search for more papers by this authorV. D. Blank, V. D. Blank Institute of High Pressure Physics, Academy of Sciences of the USSR, Troitsk Search for more papers by this authorA. E. Golobokov, A. E. Golobokov Institute of High Pressure Physics, Academy of Sciences of the USSR, Troitsk Search for more papers by this authorYu. S. Konyaev, Yu. S. Konyaev Institute of High Pressure Physics, Academy of Sciences of the USSR, Troitsk Search for more papers by this authorA. Yu. Zerr, A. Yu. Zerr Institute of High Pressure Physics, Academy of Sciences of the USSR, Troitsk Search for more papers by this authorE. I. Estrin, E. I. Estrin Institute of High Pressure Physics, Academy of Sciences of the USSR, Troitsk Search for more papers by this author M. M. Aleksandrova, M. M. Aleksandrova Institute of High Pressure Physics, Academy of Sciences of the USSR, Troitsk Search for more papers by this authorV. D. Blank, V. D. Blank Institute of High Pressure Physics, Academy of Sciences of the USSR, Troitsk Search for more papers by this authorA. E. Golobokov, A. E. Golobokov Institute of High Pressure Physics, Academy of Sciences of the USSR, Troitsk Search for more papers by this authorYu. S. Konyaev, Yu. S. Konyaev Institute of High Pressure Physics, Academy of Sciences of the USSR, Troitsk Search for more papers by this authorA. Yu. Zerr, A. Yu. Zerr Institute of High Pressure Physics, Academy of Sciences of the USSR, Troitsk Search for more papers by this authorE. I. Estrin, E. I. Estrin Institute of High Pressure Physics, Academy of Sciences of the USSR, Troitsk Search for more papers by this author First published: 16 January 1988 https://doi.org/10.1002/pssa.2211050141Citations: 9 SU-142092 Troitsk, Moscow region, USSR. AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat Citing Literature Volume105, Issue116 January 1988Pages K29-K32 RelatedInformation