Formation of nanocrystalline phases during thermal decomposition of amorphous Ni-P alloys by isothermal annealing.
The microstructure and the average grain size were investigated by x-ray diffraction and transmission electron microscopy for nanocrystalline (n) Ni-P alloys with 18, 19, and 22 at.% P. A detailed study of the nanocrystalline states obtained along different heat treatment routes has been performed: (1) a-->ni by isothermal annealing of the melt-quenched amorphous (a) Ni-P alloys; (2) ni-->nii by isothermal annealing of the nanocrystalline ni state; (3) ni-->nii by linear heating of the ni state. The heats evolved during the structural transformations were determined by differential scanning calorimetry. From these studies, a scheme of the structural transformations and their energetics was constructed, which also includes previous results on phases obtained by linear heating of the as-quenched amorphous state of the same alloys. Grain boundary energies also have been estimated. In some cases it was necessary to assume a variation of the specific grain boundary energy during the phase transformation to understand the enthalpy and microstructure changes during the different heat treatments.
Révész
A
A
Department of General Physics, Eötvös University, P.O.B. 32, H-1518 Budapest, Hungary.
Lendvai
J
J
Cziráki
A
A
Liebermann
H H
HH
Bakonyi
I
I
D000497:Alloys / Q000737:chemistry*; D002152:Calorimetry, Differential Scanning; D003460:Crystallization / Q000379:methods; D006358:Hot Temperature; D008854:Microscopy, Electron; D036103:Nanotechnology / Q000379:methods*; D009532:Nickel / Q000737:chemistry*; D010758:Phosphorus / Q000737:chemistry*; D012680:Sensitivity and Specificity; D013696:Temperature; D014961:X-Ray Diffraction
D000497:Alloys; D010758:Phosphorus; D009532:Nickel