Investigation of the Property Change in FINEMET Alloy After Conventional, Pulse and Mechanical Stress Annealing

In the present work the comparison of the effect of traditional, pulse and stress annealing is made by monitoring the important mechanical and magnetic properties of FINEMET type amorphous precursor alloy. The magnetic properties were determined from the shape of magnetization curve (coercive force, anisotropy) during various heat treatments and the mechanical properties were measured using brittleness test. The traditional heat treatments were performed in resistance furnace and the magnetic measurements were performed in astatic magnetometer. The pulse and stress annealing (as well as their combinations) were carried out inside in the magnetometer. The temperature of pulse heat treatments is regulated with the length of current pulse flowing through the sample. After each pulses the magnetization curves were measured in-situ, in the magnetometer.

Magnetic Characterization in the Rayleigh Region of Nanocrystalline Magnetic Cores

We report on the structural and magnetic characterization of two nanocrystalline Finemet-type magnetic cores. The nanocrystalline structure developed after annealing the amorphous precursor alloy at 550 °C for 30 and 60 min of annealing time. Structural analysis carried out by means of X-ray diffraction providing useful information on the grain size mean and partial volume of the nanocrystalline phase. The magnetic characterization was focused mainly in the Rayleigh region which, influenced by the intergranular coupling, was found to be more efficient in the sample treated for a longer time with a finer nanocrystalline structure.

Dealloying of Cu-Mg-Ca Alloys

The chemical dealloying of Cu-Mg-Ca alloys in free corrosion conditions was investigated for different alloy compositions and different leaching solutions. For some of the precursor alloys, a continuous, pure fcc copper with nanoporous structure can be obtained by dealloying in 0.04 M H2SO4 solution. Superficial nanoporous copper structures with extremely fine porous size were also obtained by dealloying in pure water and 0.1 M NaOH solutions. The dealloying of both amorphous and partially crystalline alloys was investigated obtaining bi-phase nanoporous/crystal composites with microstructures depending on the precursor alloy state. The fast dissolution of Mg and Ca makes the Cu-Mg-Ca system an ideal candidate for obtaining nanoporous copper structures with different properties as a function of different factors such as the alloy composition, the quenching process, and leaching conditions.

Structure analysis of precursor alloy and diffusion during dealloying of Ag–Al alloy

Nanoporous silver (NPS) was fabricated by dealloying Ag–Al alloy ribbons with nominal compositions of 30, 35 and 40 at% Ag (corresponding to hypoeutectic composition, eutectic composition and hypereutectic composition, respectively).

A Preparation Method of Patterned Nanoporous Copper

Graphic nanoporous copper (NPC) was prepared by a new method. Cu68Zn32 and Cu36Zn64 (atomic percentages) precursor alloy thin film was deposited by electro-deposition in acidic alloy plating solution and then dealloyed in hydrochloric acid to fabricate nanoporous copper (NPC) with pore size from 30nm to 100nm. The results show that the microstructure of NPC can be controlled by changing alloy plating solution and dealloying process, this process also maintains compatibility with micro-fabrication technique.