High-density (>98% of full density) nanocrystalline invar alloys with significantly enhanced hardness (>240 in Vicker’s hardness) were prepared by sintering compacted Fe-Ni nanoparticles in hydrogen. The precursor Fe-Ni nanoparticles were synthesized by hydrogen plasma evaporation of bulk Fe61Ni39 alloys. The size and the productivity of the Fe-Ni nanoparticles increased with increasing hydroge...

The formation and growth process of precipitates in Cu-Ni-Si alloys during aging were investigated by anomalous small angle scattering (ASAXS) and X-ray absorption fine structure (XAFS). ä-Ni2Si precipitates with wide nanometer size distribution were formed in the Cu-Ni-Si alloys after a long aging time of 10 s. However, the addition of a small amount of Fe appears to reduce the wide-size distr...

The nanocrystallization processes in Fe-Si-B-Nb-Cu and Fe-Nd-B(-Cu-Nb) amorphous alloys have been studied by transmission electron microscopy (TEM) and a three dimensional atom probe (3DAP). Cu additions are effective in refining the nanocrystalline microstructures of an Fe74.5Si13.5B8Nb3Cu1 alloy and an Fe3B/Nd2Fe14B nanocomposite microstructure. This is because Cu atoms form a high density of...

Nanoporous electrodes have been fabricated by selectively dissolving the less noble α-Fe crystalline phase from nanocrystalline Fe85.2B14-xPxCu0.8 alloys (x= 0, 2, 4 at.%). The preferential dissolution is triggered by the weaker electrochemical stability of α-Fe nanocrystals than amorphous phase. The final nanoporous structure is mainly composed of amorphous residual phase and minor undissolved...

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Effects of ultra high magnetic field of both pulse and steady types on martensitic transformation have been studied, using Fe-Ni-Mn, Fe-Ni-Mn-C alloys with the supplemental tests on Fe-Ni-C and Fe-NiCo-Ti alloys. It is found that the martensitic transformation is induced at room temperature not only athermally but also isothermally either by pulse magnetic field or by steady magnetic field for ...

Fe or Co based alloys with nanocrystalline microstructure show excellent permeability because the net magnetocrystalline anisotropy is significantly reduced when the grain size becomes smaller than the ferromagnetic exchange length. Fe-Si-B-Nb-Cu alloy is the pioneering nanocrystalline soft magnetic material invented by Yoshizawa et al. in 1988 [1]. Our previous works [2,3] reported evidence fo...

The effect of partial replacement of Fe by Co (up to 8 %) on thermal stability, structure and magnetic properties of FeNbBCu alloys has been explored in this paper. The results indicate that Co reduces the stability against crystallization of the amorphous alloy and stabilizes the nanocrystalline phase prior to the further precipitation of metastable boride phases. Transmission Mössbauer spectr...

Iron alloyed with Ni and Si has been suggested to be a major component of the Earth’s inner core. High-pressure results on the combined alloying effects of Ni and Si on seismic parameters of iron are thus essential for establishing satisfactory geophysical and geochemical models of the region. Here we have investigated the compressional (VP) and shear (Vs) wave velocity-density (ρ) relations, P...