Bell Helicopter

About: Bell Helicopter is a company organization based out in Mirabel, Quebec, Canada. It is known for research contribution in the topics: Rotor (electric) & Fuselage. The organization has 1214 authors who have published 1587 publications receiving 13264 citations.

A family of ductile intermetallic compounds.

Abstract: Stoichiometric intermetallic compounds have always been touted for their attractive chemical, physical, electrical, magnetic and mechanical properties, but few practical uses have materialized because they are brittle at room temperature1,2,3,4. Here we report on a large family of fully ordered, stoichiometric binary rare-earth intermetallic compounds with high ductility at room temperature. Although conventional wisdom calls for special conditions, such as non-stoichiometry, metastable disorder or doping to achieve some ductility in intermetallic compounds at room temperature, none of these is required in these unique B2 rare-earth compounds. Ab initio calculations of YAg, YCu and NiAl crystal defect energies support the observed deformation modes of these intermetallics.

Effective medium theories for artificial materials composed of multiple sizes of spherical inclusions in a host continuum

Abstract: This paper presents the application of nonempirical effective medium theories to describe composite mixtures of spherical inclusions within a host continuum. It is shown that the most common effective medium theories collapse into Bruggeman's (1935) asymmetric formula when they are implemented in an iterative scheme to extend their validity to higher volume fractions. Comparisons of DC and 4-GHz data show that of all the formulas Bruggeman's asymmetric formula corresponds best with experiment for large differences between the complex permittivities of the host and inclusion materials. Permeability values are also formulated and compared with experiment and a simple scheme is considered to extend the effective medium theories herein to a description of the diamagnetic effect of induced current in metal spherical inclusions.

Neutron Magnetic Form Factors and X‐Ray Atomic Scattering Factors for Rare‐Earth Ions

Abstract: The theory of neutron scattering by paramagnetic rare‐earth ions has been given by Trammell and more recently by Odiot and Saint‐James. Unlike the case for the iron‐series transition metals, for which the orbital angular momentum of the 3d electrons is almost completely quenched, the magnetic scattering of neutrons from the rare earths (except for gadolinium and europium) arises from both the spin and orbital contributions to the magnetization. Using recently determined Hartree—Fock wave functions for some of the trivalent rare‐earth ions we have determined the functions 〈jn〉 and 〈gn〉 (for n=0, 2, 4, and 6) which are necessary for the theoretical evaluation of the spin and orbital contributions, respectively, to the magnetic form factor. A comparison of these theoretical results with the experiments of Koehler and Wollan for Nd3+ and Er3+ and of Koehler, Wollan, and Wilkinson for Ho3+ is presented. Large differences are found between Trammell's theory and experiment and some possible reasons for this are ...