Structural transformations in high-strength magnetically hard Fe-Cr-Co-W-Ga alloys

The role of plastic deformation in the creation of high strength in hard magnetic alloys Fe-Cr-Co-W-Ga

“…The X ray diffraction patterns contain peaks of one α phase and weak peaks of the tungsten rich η' phase marked with arrows. A similar situation was observed earlier for the alloys containing α 1 and α 2 phases in [2], where it was shown that both these phases are inhomogeneous in terms of composition, which leads to a spread of the magnitudes of the lattice parameters, which in turn leads to a broadening of diffraction lines. Since the difference in the lattice parameters of the α 1 (Fe-Co) and α 2 (Fe-Cr) phases is not large, the peaks in the diffraction patterns are not resolved but merge into one broad peak.…”

“…It has been demonstrated that the strengthening of alloys with 22% Cr and 15% Co strongly depends on the degree of cold deformation with a maximum near 60% both after deformation and, particularly, after aging. It has been established [2], that in cold rolled specimens of these alloys the decomposition into α 1 and α 2 phases occurs without the formation of a modulated structure and that the process proceeds deeper in comparison with the specimens aged directly after quenching from the region of homogeneous solid solution. Moreover, in these alloys there is readily formed a disperse η' phase enriched in tungsten, whereas its formation during alloy aging directly after quenching from † Deceased.…”

Structure of a W-enriched phase in Fe–Co–Cr–W–Ga alloys

“…A preliminary investigation with the help of the Mossbauer method showed [1] that in the Mossbauer spectra of the alloys containing W one can pick out three contributions related to the high-field distribution, one contribution from the low-field distribution, and a paramagnetic contribution. Since no traces of ␥-Fe phase were detected in the X ray patterns, an assumption was made that the paramagnetic contribution can be ascribed to the W-enriched phase.…”

“…First [1], they may serve as obstacles for the dislocation motion and favor strengthening of the alloys, increasing stresses, and, consequently, growing contribution of elastic energy in the high-coercivity state. Second, small precipitates of the paramagnetic phase can hinder motion of magnetic domain walls, thus providing a coercivity of 125-190 Oe.…”

“…In our previous work [1] structure transformations were studied that take place at different stages of the treatment resulting in a highcoercivity state of the alloys. It was established that in the course of annealings at 640-600 • C in the alloys there takes place a decomposition of the high-temperature ␣-Fe based solid solution with the formation of a strong magnetic (Fe-Co enriched), weak magnetic (Fe-Cr enriched) phases and disperse W enriched phase.…”