Iron content and temperature dependences of diffuse scattering in Ti–(50–x)Ni–xFe (6 ≤ x ≤ 10) alloys

Abstract

Diffuse scatterings appearing in electron diffraction patterns of Ti–(50 − x)Ni–xFe (x = 6, 7, 8, 10, in at.%) alloys were investigated. In the alloys, martensitic (R-phase) transformation is suppressed down to 4.2 K, but the electrical resistivity exhibits a local minimum at T _min (210 K, 195 K, 180 K and 140 K for x = 6, 7, 8, 10, respectively). The following results were obtained for all the alloys. Diffuse scattering appears below T _min and its intensity maximum is located at an incommensurate position of g + ⟨ζζ0⟩*, where g is a reciprocal lattice vector of the B2-phase. The value ζ at T _min is significantly smaller than 1/3 and increases with decreasing temperature; it decreases with increasing Fe content. The value of ζ at T _min agrees with the length of nesting vector obtained by a band calculation, suggesting that the diffuse scattering is caused by the nesting effect of the Fermi surface in the B2-type structure.

Keywords:

• martensitic transformation
• precursor phenomena
• phonon softening
• electronic structure

Acknowledgments

The present work was partly supported by Priority Assistance for the Formation of Worldwide Renowned Centers of Research – The Global COE Program (Project: Center of Excellence for Advanced Structural and Functional Materials Design) from the Ministry of Education, Culture, Sports, Science and Technology, Japan.