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X-ray analysis of changes to the atomic structure around Ni associated with the interdiffusion and mechanical alloying of pure Ni and Mo powders

Cocco, Giorgio and Enzo, Stefano and Barrett, N. T. and Roberts, Kevin J. (1992) X-ray analysis of changes to the atomic structure around Ni associated with the interdiffusion and mechanical alloying of pure Ni and Mo powders. Physical Review. B, Vol. 45 (13), p. 7066-7076. eISSN 1550-235X. Article.

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DOI: 10.1103/PhysRevB.45.7066

Abstract

We have applied a combination of x-ray diffraction and x-ray-absorption spectroscopy to probe, in a self-consistent way, the bulk and local structural changes, respectively, associated with the mechanical alloying of pure metallic powders of Ni and Mo. From a careful analysis using an analytical atomic-subshell, we show that the Ni (fcc) atoms are totally involved in the alloying reaction with Mo (bcc) atoms taking up substitutional positions in the Ni (fcc) lattice. Prior to the formation of the amorphous phase, at milling times ≈10 h, an intermediate and highly distorted NiMo phase forms with an internal strain of ≈2.1×10-3. The release of this strain with milling time corresponds to an increase in the Mo content in the alloy and the nucleation of an amorphous phase together with a subsequent loss of long-range order of the Ni lattice. The resultant amorphous phase closely resembles δ-NiMo and after milling times ≈54 h has a nominal composition of Ni50Mo38. Its formation is associated with Mo in a residual but distorted bcc environment characterized by a particle size of ≈70 nm and an internal strain of 1.8×10-3. The detailed local structure around Ni atoms during this process is presented and discussed.

Item Type:Article
ID Code:649
Status:Published
Refereed:Yes
Uncontrolled Keywords:X-ray analysis, Ni atoms, Mo atoms, milling action
Subjects:Area 03 - Scienze chimiche > CHIM/02 Chimica fisica
Divisions:001 Università di Sassari > 01 Dipartimenti > Chimica
Publisher:The American Physical Society
eISSN:1550-235X
Publisher Policy:Depositato in conformità con la politica di copyright dell'Editore
Deposited On:18 Aug 2009 10:02

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