Magnetic-moment distribution and environmental effects around titanium impurities in nickel and iron matrix

Abstract

Results of elastic diffuse scattering of polarized neutrons with 4.25-\AA{} wavelength on Ni-Ti with 3.87 and 7.72 at.% of Ti and Fe-Ti with 0.84, 1.33, and 1.73 at.% of Ti are reported. The data indicate quite different behavior of the impurity in the two matrices. In the nickel-based alloys the titanium atom has negligible magnetic moment while in the Fe-Ti alloys we observe a moment enhancement at the Ti sites at low impurity concentration. Also the environmental effects are different in these two alloys. In Fe-Ti alloys, these are negligible at low impurity concentration and appear at higher impurity concentration while in the Ni-based alloys we observe an opposite effect. These results are discussed within a band model using coherent-potential approximation and we obtain an overall good description of the magnetic-moment distribution in these two alloys except in the dilute limit in Fe-Ti alloys.