Recently, the realization of the combination of selective laser melting (SLM) and high-strength aluminium alloys (Al alloys) has been discussed in mainly the aerospace industry. However, there have been several problems for the realization, and the one of fundamental problem is the occurrence of microcracks in high-strength Al alloy objects fabricated by SLM. To solve the problem, some researchers have studied addition of alloying elements to high-strength Al alloy. In this study, we focused on the A7075 alloy with additional five percent Si (A7075+5Si) and investigated the effects of the Si addition on the processability, microstructure and mechanical properties. As a result, it was observed that the addition of Si element inhibited the formation of cracks in the A7075 objects. Our result suggests the high density and crack-free A7075+5Si objects had higher mechanical properties than the case of a conventional Al alloy (AlSi10Mg and AlSi12). However, the T6 heat treatment (After solution treatment, water quenching and artificially ageing) did not increase the mechanical properties of A7075+5Si objects. In order to obtain the A7075+5Si objects with higher strength, it is required that the further studies about suitable heat treatment conditions for A7075+5Si alloy.

In this work, Cr diffused Sm₂Fe₁₇N_x core-shell magnetic powders were prepared by reduction-diffusion (RD) process. Sm₂Fe₁₇ coarse, Cr₂O₃ and Sm₂O₃ fine powders were pulverized and mixed by ball milling, and the mixed powder was heat treated following Ca addition. Cr can diffuse into Sm₂Fe₁₇ powder above 875°C in RD process, and the diffusion distance of Cr increased with increase in RD temperature. Cr diffusion distance into Sm₂Fe₁₇ powder was about 1.1-1.2 μm under RD temperature at 875°C for 1.5 h, and the Cr-diffused Sm-Fe core-shell fine powder was obtained. After nitriding and washing, Cr-diffused Sm-Fe-N fine core-shell powder was successfully obtained, and the coercivity and saturation magnetization of the core-shell powder was 855 kA·m⁻¹ and 122 Am²·kg⁻¹, respectively. The saturation magnetization was higher than non-core-shell Sm-Fe-Cr-N powder.

The dispersion of self-assembled BaTiO₃ (BT) agglomerates in poly-L-lactic-acid (PLLA) polymer matrix was decided with the multifractal analysis to investigate characters of the aggregated morphology of the secondary particle group. On the multifractal analysis, the results showed that the average secondary particle area is increased with increasing the capacity dimension (D₀). The average secondary particle area is related to BT agglomerates. It showed that S^1/2 and D₀ plot increased linearity. Therefore, BT agglomerates and D₀ have a correlation. It suggested that D₀ is related to the morphology of the BT agglomerates. The average dielectric constant (ε′) is increased with increasing D₀. It was considered that the formation of the hetero interface of BT/PLLA contributed to the increase in the average dielectric constant of BT/PLLA composites.