Abstract
Bcc La-Mg, Gd-Mg, and Dy-Mg alloys have been prepared by an ice water/acetone quench from liquid melts. Single-phase alloys could be retained in a window around the eutectoid composition: 13 to 22 at. pct Mg, 23.6 to 29 at. pct Mg, and 27 to 29 at. pct Mg for La, Gd, and Dy alloys, respectively. At the center of the windows, X-ray diffraction peaks are extremely sharp as in equilibrium bcc structures; however, as alloy composition is moved away from the eutectoid, line broadening is observed. Reversion of the bcc phase to the equilibrium micro-structure for R-Mg alloys (R = La, Gd, or Dy) has been characterized by differential thermal analysis (DTA) or differential scanning calorimetry (DSC) and isothermal annealing. La-Mg alloys revert directly to c~La (dhcp) + LaMg at about 350 °C when heated at 10 °C/min. In contrast, the Gd and Dy alloys revert by a two-step process: first, a transition to an intermediate distorted hcp phase between 300 °C and 400 °C and, second, the relaxation of this phase to αR (hcp) + RMg at about 490 °C when heated at 10 °/min. Isothermal annealing and high temperature X-ray diffraction confirm the nature of these reactions.
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J.W. Herchenroeder, P. Manfrinetti, and K.A. Gschneidner, Jr.:Physica B, 1985, vol. 135, pp. 445–48.
J.W. Herchenroeder and K.A. Gschneidner, Jr.:Bull. Alloy Phase Diagrams, 1988, vol. 9, pp. 2–12.
K.A. Gschneidner, Jr. and F.W. Calderwood: inHandbook on the Physics and Chemistry of Rare Earths, K.A. Gschneidner, Jr. and L. Eyring, ededs., North-Holland, Amsterdam, 1986, vol. 8, pp. 1–7.
P. Manfrinetti and K.A. Gschneidner, Jr.:J. Less-Common Metals, 1986, vol. 123, pp. 267–75.
B.J. Beaudry and K.A. Gschneidner, Jr.: inHandbook on the Physics and Chemistry of Rare Earths, K.A. Gschneidner, Jr. and L. Eyring, eds., North-Holland, Amsterdam, 1978, vol. 1, pp. 208–09.
B.D. Cullity:Elements of X-Ray Diffraction, 2nd ed., Addison- Wesley, Reading, MA, 1978, pp. 350–68.
J.D. Verhoeven and L.L. Jones:Metallography 1987, vol. 20, pp. 153–80.
P.G. Shewmon:Transformations in Metals, McGraw-Hill Book Co., New York, NY, 1969, p. 183.
J.W. Herchenroeder and K.A. Gschneidner, Jr.:Phys. Rev. B, 1989, vol. 39, pp. 11850–61.
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Formerly Graduate Student, Ames Laboratory and Department of Materials Science and Engineering, Iowa State University
Formerly Postdoctoral Associate, Ames Laboratory
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Herchenroeder, J.W., Manfrinetti, P. & Gschneidner, K.A. Physical metallurgy of metastable bcc lanthanide-magnesium alloys for R = La, Gd, and Dy. Metall Trans A 20, 1575–1583 (1989). https://doi.org/10.1007/BF02663191
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DOI: https://doi.org/10.1007/BF02663191