Phase transformations in pure and carbon-doped Al45Mn55 alloys

Phase transformation and magnetic properties of rapidly solidified Mn-Al-C alloys modified with Zr

“…Melt spun ribbons ($50 lm in thickness, $2 mm in width, and ranging from several centimeters to tens of centimeters in length) with compositions Mn 54Àx Al 43 C 3 Zr x (x ¼ 1, 3) and (Mn 53 Al 43 C 3 Zr 1 ) 100Àz C z (with z ¼ 1, 3, 5, 7) were obtained by rapid solidification through a single-roller melt spinner at a tangential wheel speed of 40 m/s in an Ar atmosphere. The brittle as-solidified ribbons were hand-grounded in a mortar and pestle into powders for heat treatment and analysis.…”

“…The s phase is typically formed by quenching from the high-temperature hcp e phase, followed by heat treatment at 450-600 C. [3][4][5] Since the s phase is metastable, prolonged annealing at elevated temperatures can lead to the transformation of s phase to the stable but nonmagnetic c (Al 8 Mn 5 ) and b (Mn) phases. 6 The addition of a small amount of carbon into the MnAl alloy can stabilize the s phase by inhibiting the decomposition of the s phase.…”

X-ray diffuse scattering of a decomposing hexagonal alloy

“…However, systems with hexagonal structure were not studied very intensively by the DS method because the theory was not fully developed. The present work was stimulated by recent experimental investigations of the phase transformations in the hard-magnetic Mn-Al alloys (Demin, Olihovskaya, Ustinov & Chuistov, 1987;Van Den Broek, Donkersloot, Van Tendeloo & Van Landuyt, 1979;Vlasova, Sizov & Ravdel, 1984). In these alloys the ferromagnetic ~-phase with tetragonal ordered structure (L10-type, space group P4/mmm) is formed upon decomposition of the hexagonal matrix (space group P63/mmc).…”

“…In these alloys the ferromagnetic ~-phase with tetragonal ordered structure (L10-type, space group P4/mmm) is formed upon decomposition of the hexagonal matrix (space group P63/mmc). During this transformation an intermediate ordered structure of B19 type (space group Pmcm) occurs (Vintaykin, Udovenko, Belyatskaya, Luarsabishvili & Makushew, 1974, Van Den Broek et al, 1979Vlasova et al, 1984;Demin et al, 1987).…”

Structural and Material Exploration of Magnetic Tunnel Junctions

“…As shown in Figure 8.2, the widely accepted mechanism states that during the annealing treatment, the high temperature nonmagnetic ε phase (hcp) transforms into a nonmagnetic ε' phase (orthorhombic) by an ordering reaction, then transforms into a metastable ferromagnetic τ phase (fct) by a martensitic transition [87]. Sputtering is one of the superquenching processes, but still the as-deposited MnAl thin films show almost no magnetic behavior if not deposited using elevated temperature.…”