Extended solid solubility of a CoaCr system by mechanical alloying

Mechanical alloying, MA, has been successfully used to extend the limits of solid solubility in many commercially important metallic systems. The aim of this work is to demonstrate that MA modifies the solid solubility of the CoaCr system. Co and Cr elemental powders were used as precursors and mixe...

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Bibliographic Details
Published in:Journal of alloys and compounds 2012-07, Vol.529, p.58-62
Main Authors: Betancourt-Cantera, JA, Slnchez-De Je Aos, F, Torres-Villasenor, G, Bolarin-Miro, A M, Cortes-Escobedo, CA
Format: Article
Language:English
Subjects:
Agglomeration
Alloys
Ball milling
Chromium
Mechanical alloying
Mixers
Phase transformations
Solid solubility
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Summary:Mechanical alloying, MA, has been successfully used to extend the limits of solid solubility in many commercially important metallic systems. The aim of this work is to demonstrate that MA modifies the solid solubility of the CoaCr system. Co and Cr elemental powders were used as precursors and mixed in an adequate weight ratio to obtain Co100axCrx (0 aO x aO 100, Ix = 10) to study the effect of mechanical processing in the solubility of the CoaCr system. Processing was carried out at room temperature in a shaker mixer mill using vials and balls of hardened steel as milling media with a ball: powder weight ratio of 10: 1. Crystalline structure characterization of the milled powders was conducted using X-ray diffraction, and phase transformations as a function of composition were analyzed. Thermal analysis confirmed structural changes occurred in the mechanically alloyed powders. The evolution of the phase transformations with composition is reported for each composition. The results showed that after high energy ball milling for 7 h, the solid solubility between Co and Cr could be evidently extended, despite the low solid solubility at the equilibrium conditions of this system. Additionally, the micrographs of the milled powders showed that increasing composition of chromium changes the shape and size of the particles while simultaneously reducing their agglomeration; this effect is possibly attributed to the brittleness of elemental chrome.
ISSN:0925-8388
DOI:10.1016/j.jallcom.2012.03.082