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Title: Structural, thermal, and photoacoustic study of nanocrystalline Cr{sub 3}Ge produced by mechanical alloying

A thermodynamic analysis of the Cr-Ge system suggested that it was possible to produce a nanostructured Cr{sub 3}Ge phase by mechanical alloying. The same analysis showed that, due to low activation energies, Cr-poor crystalline and/or amorphous alloy could also be formed. In fact, when the experiment was performed, Cr{sub 11}Ge{sub 19} and amorphous phases were present for small milling times. For milling times larger than 15 h these additional phases decomposed and only the nanostructured Cr{sub 3}Ge phase remained up to the highest milling time used (32 h). From the differential scanning calorimetry measurements, the Avrami exponent n was obtained, indicating that the nucleation and growth of the nanostructured Cr{sub 3}Ge phase may be restricted to one or two dimensions, where the Cr and Ge atoms diffuse along the surface and grain boundaries. In addition, contributions from three-dimensional diffusion with a constant nucleation rate may be present. The thermal diffusivity of the nanostructured Cr{sub 3}Ge phase was determined by photoacoustic absorption spectroscopy measurements.
Authors:
; ;  [1] ;  [2] ;  [3] ;  [4] ;  [5]
  1. Departamento de Engenharia Mecânica, Universidade Federal de Santa Catarina, Campus Universitário Trindade, S/N, C.P. 476, 88040-900 Florianópolis, Santa Catarina (Brazil)
  2. Universidade Federal de Santa Catarina, Campus de Araranguá, 88900-000 Araranguá, Santa Catarina (Brazil)
  3. Departamento de Física, Universidade Federal do Amazonas, 3000 Japiim, 69077-000 Manaus, Amazonas (Brazil)
  4. Departamento de Física, Universidade Federal de Santa Catarina, Campus Universitário Trindade, S/N, C.P. 476, 88040-900 Florianópolis, Santa Catarina (Brazil)
  5. Seção de Engenharia Mecânica e de Materiais, Instituto Militar de Engenharia, 22290-270 Rio de Janeiro (Brazil)
Publication Date:
OSTI Identifier:
22492829
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Applied Physics; Journal Volume: 118; Journal Issue: 15; Other Information: (c) 2015 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; 71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; ABSORPTION SPECTROSCOPY; ACTIVATION ENERGY; ALLOYS; AMORPHOUS STATE; CRYSTALS; GRAIN BOUNDARIES; MILLING; NANOSTRUCTURES; NUCLEATION; THERMAL DIFFUSIVITY; THREE-DIMENSIONAL LATTICES