Effect of Nb, Y and Zr on thermal stability of nanocrystalline Al-4.5 wt.% Cu alloy prepared by mechanical alloying

Autor: Suhrit Mula, Anil Kumar, V.M. Suntharavel Muthaiah
Rok vydání: 2017
Předmět:
Zdroj: Journal of Alloys and Compounds. 722:617-627
ISSN: 0925-8388
DOI: 10.1016/j.jallcom.2017.06.089
Popis: In the present study, effect of Nb, Y and Zr (having low equilibrium solid solubility in Al) in the formation of nanocrystalline Al-4.5 wt.% Cu-1at.% X (X = Nb, Y & Zr) solid solutions by mechanical alloying and their thermal stability have been investigated. The mechanically alloyed samples were annealed in batches for 1 h at different temperatures ranging from 150 to 550 °C. The thermal stability has been studied through X-ray diffraction (XRD) phase analysis and variation of microhardness as a function of temperature. Transmission electron microscopy (TEM) and SAED analysis showed that 1 at.% Y and 1 at.% Nb could be dissolved into Al-4.5% Cu solid solutions after mechanical alloying up to 8 h of milling. The spontaneity of formation of Al-4.5%Cu Y, Al-4.5%Cu Nb and Al-4.5%Cu Zr solid solutions has been explained from the change of Gibbs free energy as per Miedema's and Toop's models. It demonstrated that the summative energy due to the reduction in crystallite size and accumulation of dislocation density exceeds the theoretical energy barrier required for the formation of the Al-4.5%Cu Y, Al-4.5%Cu Nb disordered solid solutions. The grain sizes were found to retain Cu Nb, Al3Y and Al3Y5 in Al Cu Y and Cu10Zr7, Al3Zr and Cu5Zr in Al Cu Zr alloys.
Databáze: OpenAIRE
Externí odkaz: