R. A. Dunlap

New microcrystalline hard magnets in a Co-Zr-B alloy system

The glass formability and magnetic properties of rapidly solidified Co-Zr-B alloys were investigated in the composition range Co/sub 80/Zr/sub x/B/sub 20-x/ (2 >

Hyperfine field distributions and magnetic properties of melt-spun and sputtered Fe-rich Fe-Zr amorphous alloys

Abstract Mossbauer spectra for a range of melt-spun and sputtered alloys show bimodal hyperfine distributions, indicating that Fe atoms with all-Fe nearest neighbours are in a low-spin state. Magnetic properties of sputtered alloys are compared with those of melt-spun samples previously reported. Considerable differences are found in Curie temperatures and coercivities. The results are interpreted as showing greater inhomogeneity in sputtered material.

Physical properties of icosahedral Al─Cr─Fe─Ge alloys

Abstract Alloys of the form Al65Cr20Ge15 with up to 15 at.% Fe substituted for Cr have been rapidly solidified from the melt by single-roller melt spinning and have been shown to be single-phase icosahedral quasicrystals. X-ray diffraction measurements show an increase in disorder with increasing Fe content. Thermal analysis measurements indicate structural relaxation of the quasicrystalline phase prior to crystallization. Mossbauer spectra of all alloys exhibit a broadened doublet. These spectra are analysed in terms of models involving multiple transition metal sites and distributions of transition metal environments.

Icosahedral quasicrystals and magnetism

Abstract For several years the study of magnetic properties of quasicrystals was limited mostly to Mossbauer spectroscopy and susceptibility measurements on paramagnetic and spin-glass alloys primarily in the Al–Mn(–Si) system. A distribution of low-symmetry Mn sites appears to exist with only the larger sites (making up approximately 60% of the total) allowing a Mn moment to form. Fe and V (neither of which bears a moment in this system) appear to substitute preferentially in the non-magnetic and magnetic Mn sites respectively. Recently, ferromagnetic icosahedral quasicrystals have been discovered in the Al–Mn–Si and Al–Mn–Ge systems, broadening the field of interest as well as the range of techniques that can be brought to bear on these unusual materials. While large average effective moments can characterize paramagnetic quasicrystals (2·0 μB per Mn atom in Al60Mn20Ge20), ferromagnetic quasicrystals so far exhibit high Curie temperatures (up to 500 K) but very small magnetizations (less than 2e.m.u. g−...

Exact traveling wave solutions to nonlinear diffusion and wave equations

AbstractBy the introduction of some ansatz equations, we have obtained several new classes of traveling (solitary) wave solutions to the nonlinear diffusion equationn

Magnetic critical properties of amorphous Fe-Cr-B alloys measured by ac susceptibility techniques

f_1 (u)u_t + f_2 (u)u_x + f_3 (u)u_{xx} + f_4 (u)u_x^2 = f_5 (u)

Mössbauer effect studies of Hume-Rothery stabilization mechanisms in decagonal Al-Fe-Ni quasicrystals

n and the nonlinear wave equationn