X-RAY-DIFFRACTION STUDY OF THE EFFECTS OF BORON ON OCCURRENCE OF DEFORMATION FAULTS IN NI3AL ALLOY

Nt3Al and Ni3Al alloys containing varying amounts of boron in L1(2) ph ase were prepared. All the samples were suitably annealed and then col d-worked by hand filing. X-ray diffraction data are collected on annea led and cold-worked samples. The deformation fault probabilities have been evaluated by two methods, viz. peak shift analysis of powder patt ern X-ray reflections of annealed and cold-worked samples, and lattice parameter change between annealed and corresponding cold-worked sampl es. The values obtained by both the methods are in reasonable agreemen t. It has been found that the deformation fault probability of Ni3Al a nd Ni3Al containing boron alloys are very high compared to Ag and Cu b ase alloys. Further the deformation fault probability of Ni3Al is more sensitive to boron addition. It has been found that at least 1.22 at. % of boron goes into the Ni3Al lattice.