On amorphization and nanocomposite formation in Al-Ni-Ti system by mechanical alloying

Das, N. ; Dey, G. K. ; Murty, B. S. ; Pabi, S. K. (2005) On amorphization and nanocomposite formation in Al-Ni-Ti system by mechanical alloying Pramana - Journal of Physics, 65 (5). pp. 831-840. ISSN 0304-4289

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Official URL: http://www.ias.ac.in/pramana/v65/p831/fulltext.pdf

Related URL: http://dx.doi.org/10.1007/BF02704082


Amorphous structure generated by mechanical alloying (MA) is often used as a precursor for generating nanocomposites through controlled devitrification. The amorphous forming composition range of ternary Al-Ni-Ti system was calculated using the extended Miedema's semi-empirical model. Eleven compositions of this system showing a wide range of negative enthalpy of mixing (-ΔH mix) and amorphization (-ΔH amor) of the constituent elements were selected for synthesis by MA. The Al88Ni6Ti6 alloy with relatively small negative ΔH mix (-0.4 kJ/mol) and ΔHamor (-14.8 kJ/mol) became completely amorphous after 120 h of milling, which is possibly the first report of complete amorphization of an Al-based rare earth element free Al-TM-TM system (TM = transition metal) by MA. The alloys of other compositions selected had much more negative ΔHmix and Hamor; but they yielded either nanocomposites of partial amorphous and crystalline structure or no amorphous phase at all in the as-milled condition, evidencing a high degree of stability of the intermetallic phases under the MA environment. Hence, the negative ΔH mix and ΔH amor are not so reliable for predicting the amorphization in the present system by MA.

Item Type:Article
Source:Copyright of this article belongs to Indian Academy of Sciences.
Keywords:Nanocomposite; Amorphization; Mechanical Alloying; Miedema Model; Al-Ni-Ti System
ID Code:9556
Deposited On:02 Nov 2010 11:56
Last Modified:16 May 2016 19:21

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