Physical metallurgy of metastable Bcc lanthanide-magnesium alloys for R = La, Gd, and Dy

Journal Article · Fri Sep 01 04:00:00 EDT 1989 · Metallurgical Transactions, A (Physical Metallurgy and Materials Science); (USA)

DOI:https://doi.org/10.1007/BF02663191· OSTI ID:6902670

Herchenroeder, J W ^[1]; Manfrinetti, P ^[2]; Gschneidner, Jr, K A ^[3]

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1. Delco Remy, Div. of General Motors Corp., IN (US)
2. via acquistapace 4/5, 15067 Novi Ligure, AL (IT)
3. Ames Lab. and Dept. of Materials Science and Engineering, Iowa State Univ., Ames, IA (US)

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 microstructure 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 {alpha}La (dhcp) + LaMg at about 350{degrees}C when heated at 10{degrees}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{degrees}C and 400{degrees}C, and, second, the relaxation of this phase to {alpha}R (hcp) + RMg at about 490{degrees}C when heated at 10{degrees}C/min. Isothermal annealing and high temperature x-ray diffraction confirm the nature of these reactions.

• OSTI ID: 6902670
• Journal Information: Metallurgical Transactions, A (Physical Metallurgy and Materials Science); (USA), Journal Name: Metallurgical Transactions, A (Physical Metallurgy and Materials Science); (USA) Vol. 20A:9; ISSN MTTAB; ISSN 0360-2133
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360102* -- Metals & Alloys-- Structure & Phase Studies
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400101 -- Activation
Nuclear Reaction
Radiometric & Radiochemical Procedures
ALLOY SYSTEMS
ALLOYS
ANNEALING
BCC LATTICES
BINARY ALLOY SYSTEMS
CHEMICAL PREPARATION
COHERENT SCATTERING
CRYSTAL LATTICES
CRYSTAL STRUCTURE
CUBIC LATTICES
DIFFERENTIAL THERMAL ANALYSIS
DIFFRACTION
DYSPROSIUM ALLOYS
ENERGY LEVELS
EXCITED STATES
GADOLINIUM ALLOYS
HEAT TREATMENTS
ISOTHERMAL PROCESSES
LANTHANUM ALLOYS
MAGNESIUM ALLOYS
METASTABLE STATES
QUENCHING
RARE EARTH ALLOYS
SCATTERING
SYNTHESIS
THERMAL ANALYSIS
X-RAY DIFFRACTION