Surface Precipitation in Gold and Tungsten Containing Iron-based Alloys and Steels

Self-healing materials have recently drawn the attention of industry as a new solution to the degradation of materials. Recent progress on the field of autonomous self-healing metals has been in the line of self-healing creep-resistant steels. This is challenging due to the nanometer scale of the creep cavities and the fact that only 3D...

In-situ characterization of grain nucleation and coarsening in metallic microstructures using synchrotron radiation

The research described in this thesis encompasses fields of 3DXRD, phase transformations and grain coarsening in iron alloys.

Thermal spin pumping and magnon-phonon-mediated spin-Seebeck effect

The spin-Seebeck effect (SSE) in ferromagnetic metals and insulators has been investigated systematically by means of the inverse spin-Hall effect (ISHE) in paramagnetic metals. The SSE generates a spin voltage as a result of a temperature gradient in a ferromagnet, which injects a spin current into an attached paramagnetic metal. In the...

Defect evolution during annealing of deformed FeSi alloys studied by positron annihilation spectroscopy

High silicon steel is widely used in electrical appliances. Alloying iron with silicon improves its magnetic performance. A silicon content up to 6.5 wt. % gives excellent magnetic properties such as high saturation magnetization, near zero magnetostriction and low iron loss in high frequencies. Their workability is greatly reduced by the...

Bidirectional current-voltage converters based on magnetostrictive/piezoelectric composites

We report a power supply-free, bidirectional electric current-voltage converter based on a coil-wound laminated composite of magnetostrictive alloy and piezoelectric crystal. An electric current applied to the coil induces a magnetic field, resulting in an electric voltage from the composite due to the direct magnetoelectric effect. Conversely,...

Tunable thermal hysteresis in MnFe(P,Ge) compounds

Structural, magnetic, and magnetocaloric properties of the MnFe(P,Ge) compounds were systematically studied on both bulk alloys and melt-spun ribbons. The experimental results show that the critical behavior of the phase transition can be controlled by changing either the compositions or the annealing conditions. The thermal hysteresis is found...

Nonreciprocal spin wave spectroscopy of thin Ni–Fe stripes

The authors report on the observation of nonreciprocal spin wave propagation in a thin ( ? 200?nm) patterned Ni–Fe stripe. The spin wave transmission spectrum is measured using a pair of microstrip lines as antennas. The nonreciprocity of surface wave dispersion brought about by an adjacent aluminum ground leads to a nonreciprocal coupling of...

10?GHz bandstop microstrip filter using excitation of magnetostatic surface wave in a patterned Ni78Fe22 ferromagnetic film

Various microstrips with a ferromagnetic core were designed and fabricated on a silicon substrate. The core was formed by a 0.5-?m-thick Ni78Fe22 film, patterned into rectangular prisms. Measurement results for attenuation constant versus frequency show a peak value of ? 50?dB/cm around 10?GHz. Electromagnetic simulations show that the...

Effect of the geometry in modeling the kinetics of diffusional transformations in substitutional iron alloys

Role of interface mobility on the kinetics of diffusional transformation in Fe-C and Fe-Mn alloys

Kinetics of internal nitriding of an Fe-7at.% Al alloy

Redistribution of carbon during the austenite to ferrite transformation in pure Fe-C alloys

Compressibility and fugacity of gaseous hydrogen

The concept of fugacity is explained. Application of compressibility and fugacity data in hydrogen embrittlement calculations is discussed. Equations of state are reviewed. Compressibility factors and fugacity coefficients are calculated. A best estimate is proposed.

Coarsening and solutioning of precipitates in superalloys

Coarsening and solutioning of the main strengthening phase for the majority of superalloys, the y' phase, are discussed. It is shown that a general prediction of coarsening rates and solutioning temperatures is possible.