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Investigation of Grain Boundary Compositions and Magnetic Properties of Hot-Worked Nd_{18}Tb_1Fe_{66.5}Co_5Al_{1.5}B_8 Magnets

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Sadullahoğlu G., Altuncevahir B., Okan Addemir A.

Acta Physica Polonica A

2013

vol. 123

issue 2

233-234

Magnetic properties which are related to the compositions on the grain boundaries of the NdFeB permanent magnets were studied at different hot working temperatures applied to the cast Nd_{18}Tb_1Fe_{66.5}Co_5Al_{1.5}B_8 ingots. Since the addition of Al caused the formation of hard magnetic μ phase between the magnetic NdFeB crystals after the pressing 800C H_{c} value increased to the highest value of 8.21 kOe. According to the SEM micrographs and EDS analysis, the increase in pressing temperature, the atomic ratios in the NdFeAl compositions approached to hard magnetic μ phase with the increase in pressing temperature and its exact composition was obtained in the sample hot deformed at 800°C. Although the secondary μ phase with a high melting temperature is detremental to the alignment of c axis of the magnetic NdFeB grains along the pressing direction, we found that the magnetic properties of the magnets improve due to the presence of this hard magnetic phase on the grain boundaries.

Gamma Attenuation Behavior of h-BN and h-BN-TiB_2 Composites

100%

Buyuk B., Beril Tugrul A., Okan Addemir A., Ay N.

Acta Physica Polonica A

2014

vol. 125

issue 2

420-422

Hexagonal boron nitride (h-BN) and hexagonal boron nitride-titanium diboride (h-BN-TiB_2) composites are advanced materials for high-tech applications. They were investigated against gamma radioisotope sources Cs-137 and Co-60 which have gamma peaks 0.662 MeV for Cs-137, and 1.17 and 1.33 MeV for Co-60. Materials have been produced at 1800C temperature in argon atmosphere without pressure during 2 h time. Linear and mass attenuation coefficients were calculated for the materials. Gamma transmission technique was used in the experiments. The experimental investigated mass attenuation coefficients of the materials for Cs-137 and Co-60 gamma radioisotope sources were compared with XCOM computer code. For h-BN-TiB_2 composites the ratio of TiB_2 in the composites is 55% by weight. So gamma attenuation effects of adding TiB_2 to h-BN were discussed. It could be said that adding TiB_2 to h-BN increases the linear gamma attenuation of the samples.

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2 Acta Physica Polonica A

1 2014

1 2013

2 Okan Addemir A.

1 Altuncevahir B.

1 Ay N.

1 Beril Tugrul A.

1 Buyuk B.

1 Sadullahoğlu G.

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Investigation of Grain Boundary Compositions and Magnetic Properties of Hot-Worked Nd_{18}Tb_1Fe_{66.5}Co_5Al_{1.5}B_8 Magnets

Gamma Attenuation Behavior of h-BN and h-BN-TiB_2 Composites