J. Phys. IV France 11 (2001) Pr8-439-Pr8-444
Nanoscale inhomogeneities in melt-spun Ni-AlP.L. Potapov1, P. Ochin2, J. Pons3 and D. Schryvers1
1 Electron Microscopy for Materials Research (EMAT), University of Antwerp, RUCA, Groenenborgerlaan 171, 2020 Antwerp, Belgium
2 Laboratoire de Métallurgie Structurale, ENSCP, 11 rue Pierre et Marie Curie, 75231 Paris cedex 05, France
3 Departament de Fisica, Universitat de les Illes Balears, Ctra. de Valldemossa km 7.5, 07071 Palma de Mallorca, Spain
Ni-Al material consisting 62 ...65%Ni was rapidly quenched to room temperature by the meltspinning technique and studied using X-ray diffraction, different transmission electron microscopy (TEM) modes and calorimetry measurements. Similar to bulk material, the initial B2 structure undergoes a martensitic transformation to the L1o or 14M structure. However, the transformation proceeds very inhomogeneously and results in a mixed microstructure consisting of transformed and untransformed regions. The structure of the transformed regions varies from faulted L1o to faulted 14M and shows a variety of morphological features. EDX and EELS nanoprobes reveal that the special structural state of the melt-spun material is explained mainly by solute segregation appearing during the crystallisation process. Thus, contrary to most of other melt quenched materials, in Ni-Al, solute segregation can not be suppressed by the rapid quenching procedure. Ageing at 1200°C restores the compositional homogeneity and results in more homogenious martensitic transformation resembling that in bulk Ni-Al material.
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