Superconducting properties of nanocrystalline Nb3Al in Nb-Al matrix

We present the results of x-ray diffraction and magnetization measurements on the nanocrystalline as-cast compound Nb3Al. X-ray diffraction shows the presence of the A15 Nb3Al phase embedded in a matrix of a bcc Nb-Al solid solution. The average grain size of Nb3Al estimated from the line broadening is about 35 nm. Magnetization measurements give a lower limit of the superconducting transition temperature to be about 16.8 K, which is amongst the highest known T-C for the as-cast sample of Nb3Al. In the superconducting state, the sample shows anomalous thermomagnetic history effects in the temperature and field variation of magnetization. (C) 2008 American Institute of Physics.