Determination of long range order and vacancy content in the NiAl β′-phase alloys by x-ray diffractometry

摘要: Abstract The long range order in the β′-phase alloys Ni1−cAlc (0.46 ⩽ c 0.54) with L20-type structure was investigated by powder X-ray diffractometry. Integrated intensities for eight reflections distributed over a wide angle were measured and least-squares calculation performed based on profile fitting method. In Al-rich side, concentration of vacancies their preferred lattice site determined. results summarized as: (1) atomic arrangement Ni-rich side attained practically maximum ordered state; (2) vacancy content increased linearly Al content; (3) preferentially occupied Ni-sites (with probability about 3 4 ), while major portion Ni atoms own sites. These conclusions supported performing Rietveld analysis all samples.