Thermal stability and grain growth behavior of mechanically alloyed nanocrystalline Fe-Cu alloys

Journal Article · Thu Dec 31 23:00:00 EST 1992 · Journal of Applied Physics; (United States)

DOI:https://doi.org/10.1063/1.353890· OSTI ID:7124311

Eckert, J; Holzer, J C; Johnson, W L ^[1]

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1. California Institute of Technology, W. M. Keck Laboratory of Engineering Materials 138-78, Pasadena, California 91125 (United States)

X-ray diffraction, transmission electron microscopy, and differential scanning calorimetry were used to study the thermal stability of highly supersaturated nanocrystalline Fe[sub [ital x]]Cu[sub 100[minus][ital x]] alloys (10[le][ital x][le]95) synthesized by mechanical alloying. Alloys with [ital x][lt]60 exhibit single-phase fcc structure while single-phase bcc alloys form for [ital x][gt]80. For 60[le][ital x][le]80 fcc and bcc phases coexist. Heating to elevated temperatures leads to structural relaxation, phase separation, and grain growth of the metastable nanocrystalline solid solutions. Single-phase fcc and bcc alloys undergo significant strain release but no appreciable grain growth prior to phase separation. After phase separation pronounced grain growth sets in. In contrast, samples in the two-phase region show some grain growth and significant chemical redistribution even at low temperatures. The phase separation of single-phase fcc and bcc alloys proceeds via different mechanisms: fcc solid solutions decompose by forming small Fe precipitates, while demixing in bcc alloys starts by segregation of Cu atoms to bcc grain boundaries before nucleation of Cu precipitates. These results show that the stability and grain growth behavior of nanocrystalline alloys is strongly affected by the microstructure of the material.

• DOE Contract Number: FG03-86ER45242
• OSTI ID: 7124311
• Journal Information: Journal of Applied Physics; (United States), Journal Name: Journal of Applied Physics; (United States) Vol. 73:1; ISSN JAPIAU; ISSN 0021-8979
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360102* -- Metals & Alloys-- Structure & Phase Studies
ALLOYS
CALORIMETRY
COHERENT SCATTERING
COPPER ALLOYS
DIFFRACTION
ELECTRON MICROSCOPY
GRAIN GROWTH
IRON ALLOYS
MICROSCOPY
PHASE STUDIES
SCATTERING
STABILITY
TEMPERATURE EFFECTS
TRANSMISSION ELECTRON MICROSCOPY
X-RAY DIFFRACTION