Properties of Fe-Zr-N Thin Films
Gases emerging from Fe-Zr-N films with various compositions during heating were analyzed by thermal desorption spectroscopy. The structures and magnetic properties of films were also investigated. H2, N2 and Ar were detected at 300-400°C, 500°C and 650°C, respectively. Larger amounts of N2 were emitted by films which contained larger amounts of N2. The changes in composition of films due to the emerging N2 is as follows. The composition changed for N/Zr ratios ranging from N/Zr≫1 to N/Zr~1, but was unchanged when N/Zr1. A (100) preferred orientation occurred in films in which the composition was N~Zr≫8 at% in the as-deposited state, while either a (100) orientation or random orientation occurred in all other cases. Under the former conditions, Fe-Zr-N films showed excellent soft magnetic properties and thermal stability up to 700°C.
Fe-(Ta, Nb, Zr)-N系合金薄膜の組織と磁気持性
Microstructures and magnetic properties of Fe- (Ta, Nb, Zr)-N alloy films near the eutectic composition were studied. These new soft magnetic alloy films were prepared by N2 reactive sputtering. The structures and magnetic properties were changed by annealing or adjusting N2 partial pressure ratio. The film structures were investigated with X-ray diffraction and TEM, and the following results were obtained. (i) the as prepared films; amorphous like phase, (ii) the annealed films; homogeneous mixture of fine-grained α-Fe and (Ta, Nb, Zr) nitrides, (iii) the films annealed at higher temperatures; composite of grown grains of α-Fe and (Ta, Nb, Zr) nitrides. Among these films, the films (ii) exhibit good soft magnetic properties, small magnetostriction and high saturation magnetization up to 1.6 T. Furthermore, Fe-Ta-Zr-N alloy films show higher thermal stability of the soft magnetic properties.
Neutron Residual Stress Measurements on Rail Sections for Different Production Conditions
Rail sectioning with subsequent neutron diffraction experiments has been used to assess residual stresses in the rails. In this study we present the results of neutron stress measurements performed at the NIST Center for Neutron Research (NCNR) on rail sections from rails that were produced under various conditions. Specifically, these are air-cooled, air-cooled and roller-straightened, head-hardened and head-hardened and roller-straightened. More significantly, a head-hardened and roller-straightened rail was also studied after service to elucidate evolution of the service-induced residual stresses. In the latter case both a transverse-cut slice and the central region of a 0.53 m long piece were studied. Measurements on this piece are the first in which triaxial stresses have been determined for an intact rail. Neutron strain measurements with 3×3×3 mm3 spatial resolution were successfully employed for transversally cut slices to verify the difference in the stress state depending on the production process. Although examination of slices allows determination of only two-dimensional stresses in the plane of the slice, additional measurements on obliquely-cut slices, which were also carried out, and utilization of FEM gives the possibility of reconstructing the full triaxial stress distribution. Together, these approaches provide a better understanding of rail fabrication and the possibility of improving the durability and safety of rails in the future.Copyright © 2004 by ASME