• 한국재료학회지
• /
• 제28권10호
• /
• pp.583-589
• /
• 2018

This study investigates the effect of fatigue stress on the damping capacity in a damaged Fe-22Mn-12Cr-3Ni-2Si-4Co damping alloy under fatigue stress. ${\alpha}^{\prime}$ and ${\varepsilon}-martensite$ forms by fatigue stress in the damaged Fe-22Mn-12Cr-3Ni-2Si4-Co damping alloy under fatigue stress. The ${\alpha}^{\prime}$ and ${\varepsilon}-martensite$ forms with the specific direction and surface relief, or they cross each other. With an increasing fatigue stress, the volume fraction of ${\alpha}^{\prime}-martensite$ and ${\varepsilon}-martensite$ increases. With an increasing fatigue stress, the damping capacity increases with an increase in the volume fraction of ${\varepsilon}-martensite$. The increase in the damping capacity in the damaged Fe-22Mn-12Cr-3Ni-2Si-4Co alloy under fatigue stress strongly affects the increase of ${\varepsilon}-martensite$ formed by fatigue stress, but the damping capacity of the damaged Fe-22Mn-12Cr-3Ni-2Si-4Co damping alloy under fatigue stress is strongly controlled by a large amount of ${\alpha}^{\prime}-martensite$.

• 한국자기학회:학술대회 개요집
• /
• 한국자기학회 1997년도 춘계연구발표회 논문개요집
• /
• pp.80-81
• /
• 1997

• 한국자기학회:학술대회 개요집
• /
• 한국자기학회 1991년도 춘계연구발표회 논문개요집
• /
• pp.53-54
• /
• 1991

• 한국분말야금학회:학술대회논문집
• /
• 한국분말야금학회 1993년도 추계학술강연 및 발표대회강연 및 발표논문 초록집
• /
• pp.45-45
• /
• 1993

• 한국자기학회:학술대회 개요집
• /
• 한국자기학회 1993년도 춘계연구발표회 논문개요집
• /
• pp.58-59
• /
• 1993

• 한국자기학회:학술대회 개요집
• /
• 한국자기학회 1993년도 춘계연구발표회 논문개요집
• /
• pp.60-61
• /
• 1993

• 연구논문집
• /
• 통권29호
• /
• pp.141-149
• /
• 1999

Brazing of Fe-Cr-Al alloy was carried out at $1200^{\circ}C$ in vacuum furnace using nickel-based filler metals : BNi-5 powder(Ni-Cr-Si-Fe base alloy} and MBF-50 foil (Ni-Cr-Si-B). The effect of boron content on the stability of oxide scale on the brazed joint was investigated by means of cyclic oxidation test performed at $1050^{\circ}C$ and $1200^{\circ}C$. Apparently, the joints brazed with MBF-50 containing boron showed relatively stable oxidation rates compared to boron-free BNi-5 at both temperatures. However, it was considered that the slower weight loss of MBF-50 brazed specimen wasn’t resulted from the low oxidation rate but from the spallation of oxide layer. The oxide layer consisted of thick spinel oxide on the surface and $Al_2 O_3$ internal oxide layer along the interface between mother alloy and braze, the mother alloy was also eroded seriously by the formation of spinel oxides such as $FeCr_2 O_4$ and $NiCr_2 O_4$ on the surface, likely to be induced by the change of oxide forming mechanism due to diffusion of boron from the braze. On the contrary, the joint brazed with BNi-5 showed the good oxidation resistance during the cyclic oxidation test. It seems that the oxidation can be retarded by the formation of stable $Al_2 O_3$ layer at the surface.

• 열처리공학회지
• /
• 제29권6호
• /
• pp.264-271
• /
• 2016

The effect of the oxygen content and the annealing temperature on the tensile behavior of the Ti-1.5Al-3Fe-0.25Si-(0.1~0.5)O alloy was investigated. The tensile properties were dependent on the volume fraction of the microstructure constituents, i.e. the equixed ${\alpha}$, equixed ${\beta}$ and lamellar ${\alpha}$. The results showed that the O-partitioned equixed ${\alpha}$ had a much higher strength compared to the equixed ${\beta}$. The strength of the lamellar ${\alpha}$ increased with increasing the annealing temperature because the O content of the lamellar ${\alpha}$ increased. Ti-1.5Al-3Fe-0.25Si-0.3O alloy annealed to $900^{\circ}C$ where the volume fraction of lamellar ${\alpha}$ was the highest exhibited an excellent combination of the strength (1198.5 MPa) and ductility (27.5%). The effect of the lamellar ${\alpha}$ on the ductility was discussed.

• Journal of Magnetics
• /
• 제14권2호
• /
• pp.71-74
• /
• 2009

The magnetic and structural properties of FINEMET (the Hitachi product name of the Fe-Si-B-Nb-Cu alloy) nanopowder with a composition of $Fe_{73.5}Si_{13.5}B_9Nb_3Cu_1$ atomic percent were investigated after annealing, chemical etching, and mechanical milling. The primary and secondary crystallization temperatures were 523 and $550^{\circ}C$, respectively. The grain size of the particles was adjusted by annealing time. Optimally annealed particles exhibited a homogenous microstructure composed of nanometer-sized crystalline grains. The grain boundary of the annealed particles was etched preferentially by chemical etching. Chemically etched particles were broken at the grain boundary by high-energy ball milling. As a result, a nanometer-sized FINEMET powder with a uniform size of crystalline grains was fabricated.

• 대한금속재료학회지
• /
• 제46권1호
• /
• pp.44-51
• /
• 2008

The effects of magnetic powder size on electromagnetic wave absorption characteristics in Fe-6.5Si-0.9Cr(wt%) alloy flakes/polymer composite sheets available for quasi-microwave band have been investigated. The composite sheet including small magnetic flakes with the size less than $26{\mu}m$ exhibited high power loss in the GHz frequency range as compared with the sheets having large alloy flakes of $45{\sim}75{\mu}m$. Moreover, both the complex permeability and the loss factor increased with the decrease in size of the alloy flakes. The large power loss of the sheets containing small magnetic flakes was attributed to the high complex permeability, especially their imaginary part. The high complex permeability of the sheets composed of small flakes was considered to be due to the highly thin shape of the flakes inducing low eddy-current loss.