Title :
Influence of transformation heat treatment on microstructure and defects in RHQT-processed Nb3Al
Author :
Buta, Florin ; Sumption, Michael D. ; Collings, Edward W.
Author_Institution :
Dept. of Mater. Sci. & Eng., Ohio State Univ., Columbus, OH, USA
fDate :
6/1/2003 12:00:00 AM
Abstract :
Nb-Al jelly-roll composite wires of stoichiometric composition (25 at% Al) have been processed by Rapid Heating-Quenching (RHQ) to temperatures just above the bcc formation reaction. Transformation heat treatments going to 800°C and 1000°C with various initial heating ramp-up times (from 30 sec to 30 min) and followed by 800°C/10 hrs were applied to samples so obtained. The microstructure and planar defect distribution were investigated by transmission electron microscopy; the concentration of planar defects was found to decrease as the initial heating rate is increased. In situ high temperature X-ray diffraction studies were used to investigate the transformation heat treatment. It is proven that less ordering of the bcc solid solution prior to conversion to A15 occurs at high heating rates.
Keywords :
X-ray diffraction; aluminium alloys; composite superconductors; crystal microstructure; extended defects; heat treatment; niobium alloys; quenching (thermal); solid solutions; solid-state phase transformations; transmission electron microscopy; 800 to 1000 degC; A15 phase; BCC solid solution; Nb-Al jelly-roll composite wire; Nb3Al; Nb3Al superconductor; X-ray diffraction; microstructure; planar defect distribution; rapid heating-quenching processing; transformation heat treatment; transmission electron microscopy; Heat treatment; Heating; High temperature superconductors; Microstructure; Niobium; Solids; Superconducting magnets; Superconducting materials; Superconducting transition temperature; Superconductivity;
Journal_Title :
Applied Superconductivity, IEEE Transactions on
DOI :
10.1109/TASC.2003.812357