Phase equilibria,diffusion growth and diffusivities in Ni-Al-Pt system using Pt/β-NiAl diffusion couples

• Published in: Progress in natural science Vol. 21; no. 3; pp. 221 - 226
• Main Authors: GONG, Wei-yan, ZHANG, Li-jun, WEI, Hai-xia, ZHOU, Chun-gen
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.06.2011
• Subjects: aluminides; diffusion; equilibria; group; nickel; nickel aluminides; phase; phase equilibria; platinum; platinum group; thermodynamic; platinum group; thermodynamic; diffusion; phase equilibria; nickel aluminides
• ISSN: 1002-0071
• DOI: 10.1016/S1002-0071(12)60034-3

<正>The phase equilibria,diffusion growth and diffusivities in the Ni-Al-Pt system at 1 150,1 200 and 1 250℃were studied using Pt/β-NiAl diffusion couples.Based on the measured concentration profiles coupled with the local equilibrium hypothesis,the tie-lines between neighboring phases were determined.Two intermediate phases,Pt3Al andα-NiPt（Al）,are found to develop between the Pt andβ-NiAl couples.The thicknesses of Pt3Al andα-NiPt（Al） layers varies linearly with the square of annealing time, indicating that the growth of Pt3Al andα-NiPt（Al） are diffusion-controlled.The calculated Arrhenius equations of the parabolic growth constants,k,for the Pt3Al andα-NiPt（Al） phases are obtained,respectively.The average ternary inter-diffusivities of the Pt3Al andβ-NiAl phases at different temperatures are determined from an integration of inter-diffusion fluxes calculated directly from the experimental concentration profiles.