Boralyn (Al/B4C) composite material is produced chiey of boron carbide and aluminum. Boron Carbide is an important material for the nuclear industry due to high neutron absorption cross-section. This composite is used as shielding materials to absorb neutrons in the nuclear reactors and control road materials. In this study we investigated Al/B4C composites against gamma radiation. For that purpose, 5 wt.%, 10 wt.%, 15 wt.% and 20 wt.% reinforcement content were investigated. Cs-137 gamma radioisotope source which has 662 keV gamma energy photons were used. For each material, linear and mass attenuation coecients were calculated. Theoretical mass attenuation coecients were calculated from XCOM computer code. The theoretical results were compared with experimental results. The results were showed that increasing the amount of Boron Carbide compound content of boralyn composite material decrease the linear and mass attenuation coecient of materials
Hexagonal boron nitride (h-BN) based ceramics have been fabricated by hot-pressing in a
nitrogen atmosphere at 1900°C for 60 min. under a pressure of 50 MPa with B2O3 as sintering
additive. The phase composition was confirmed by XRD. The microstructural properties of h-BN
powders and hot-pressed surfaces were evaluated by SEM-EDS analysis. The formation of the
secondary phase was also investigated with particular interest on grain boundaries. The sintered
densities were also determined by Archimedes’ method. The maximum relative density was
obtained to be about 92 %. The effect of the existence of boron oxide on the boron nitride grain
growth behaviour was discussed on the basis of microstructural features.
With the addition of Al and/or Cu into the NdFeB based magnet, the soft free iron phase was not observed in the cast alloys while it exists in the microstructure of the undoped NdFeB ingots. For the undoped sample, free iron disappeared after hot deformation process. Grain orientation is not good and there are deviations in the growth direction of the lamellar grains which are not perpendicular to the pressing direction. On the other hand, there is a striking change that the intergranular chemistry of Al added ingot separated into Nd-rich phase and a ternary FeNdAl composition most probably formed at the pressing temperature of 750• C. The highest remanent magnetization of 7.47 kG obtained for this sample, it might be due to the hard magnetic properties of this ternary composition. For the AlCu added sample, the high Hc and Br values of 7.71 kOe and 7.33 kG, respectively, can be attributed to the homogeneous distribution of the intergranular composition and good orientation of the magnetic grains by hot deformation process.
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