Alloying behaviour in nanocrystalline materials during mechanical alloying

Pabi, S. K. ; Manna, I. ; Murty, B. S. (1999) Alloying behaviour in nanocrystalline materials during mechanical alloying Bulletin of Materials Science, 22 (3). pp. 321-327. ISSN 0250-4707

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The alloying behaviour in a number of systems such as Cu-Ni, Cu-Zn, Cu-Al, Ni-Al, Nb-Al has been studied to understand the mechanism as well as the kinetics of alloying during mechanical alloying (MA). The results show that nanocrystallization is a prerequisite for alloying in all the systems during MA. The mechanism of alloying appears to be a strong function of the enthalpy of formation of the phase and the energy of ordering in case of intermetallic compounds. Solid solutions (Cu-Ni), intermetallic compounds with low ordering energies (such as Ni3Al which forms in a disordered state during MA) and compounds with low enthalpy of formation (Cu-Zn, Al3Nb) form by continuous diffusive mixing. Compounds with high enthalpy of formation and high ordering energies form by a new mechanism christened as discontinuous additive mixing. When the intermetallic gets disordered, its formation mechanism changes from discontinuous additive mixing to continuous diffusive one. A rigorous mathematical model, based on iso-concentration contour migration method, has been developed to predict the kinetics of diffusive intermixing in binary systems during MA. Based on the results of Cu-Ni, Cu-Zn and Cu-Al systems, an effective temperature (Teff) has been proposed that can simulate the observed alloying kinetics. The Teff for the systems studied is found to lie between 0.42-0.52T1.

Item Type:Article
Source:Copyright of this article belongs to Indian Academy of Sciences.
Keywords:Nanocrystalline Materials; Mechanical Alloying; Alloying Mechanism; Alloying Kinetics
ID Code:18829
Deposited On:17 Nov 2010 12:19
Last Modified:17 May 2016 03:29

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