The Fe-based self-fluxing alloy powders and TiC particles were ball-milled and subsequently compacted and sintered at various temperatures, resulting in the TiC particle-reinforced Fe self-fluxing alloy hybrid composite, and the microstructure and micro-hardness were investigated. The initial Fe-based self-fluxing alloy powders and TiC particles showed the spherical shape with a mean size of approximately 80 and the irregular shape of less than 5 , respectively. After ball-milling at 800 rpm for 5 h, the powder mixture of Fe-based self-fluxing alloy powders and TiC particles formed into the agglomerated powders with the size of approximately 10 that was composed of the nanosized TiC particles and nano-sized alloy particles. The TiC particle-reinforced Fe-based self-fluxing alloy hybrid composite sintered at 1173 K revealed a much denser microstructure and higher micro-hardness than that sintered at 1073 K and 1273 K.

In order to fabricate the porous metal with controlled pore characteristics, unique processing by using metal oxide powder as the source and camphene as the sublimable material is introduced. CuO powder was selected as the source for the formation of Cu metal via hydrogen reduction. Camphene-based CuO slurry, prepared by milling at with a small amount of dispersant, was frozen at . Pores were generated subsequently by sublimation of the camphene. The green body was hydrogen-reduced at for 30 min, and sintered at for 1 h. Microstructural analysis revealed that the sintered Cu showed aligned large pore channels parallel to the camphene growth direction, and fine pores are formed around the large pore. Also, it showed that the pore size was controllable by the slurry concentration.

Sm-16.7wt%Co alloy powders were prepared by high energy ball milling under the conditions of various milling time and the content of process control agent (PCA), and their microstructure and magnetic properties were investigated to establish optimum processing conditions. The initial powders employed showed irregular shape and had a size ranging from 5 to . After milling for 5 h, the shape of powders changed to round shape and their mean powder size was approximately , which consisted of the agglomerated nano-sized particles with 15 nm in diameter. The coercivity was reduced with increasing the milling time, whereas the saturation magnetization increased. As the content of PCA increased, the powder size minutely decreased to approximately at the PCA content of 10 wt%. The XRD patterns showed that the main diffraction peaks disappeared apparently after milling, indicating the formation of amorphous structure. The measured values of coercivity were almost unchanged with increasing the content of PCA.

The aging characteristics of gas atomized Mg-6 wt.% Al-1 wt.% Zn alloy were investigated and compared to those of cast Mg-6 wt.% Al alloy. The gas atomized Mg-6 wt.% Al-1wt.% Zn alloy powders had spherical morphology between 1 and 100 in diameter. After compaction under the pressure of 700 MPa at for 10 min, the Mg-6 wt.% Al-1 wt.% Zn alloy showed a grain size of approximately 40 which is smaller than that of the cast Mg-6 wt.% Al alloy, and a relative compact density of approximately 93%. After ageing, the Mg-6 wt.% Al-1 wt.% Zn alloy showed much faster peak hardness than cast Mg-6 wt.% Al alloy. The Mg-6 wt.% Al-1 wt.% Zn alloy showed the new fine precipitations with ageing time, while the cast Mg-6 wt.% Al alloy was almost similar morphology.

Aging characteristics and mechanical properties of commercial 7xxx series Al composites were investigated from viewpoint of ceramic contents. After sintering process, sintered densities of blended and composite powder were 95 and 97%, respectively. Each part was solution-treated at for 60 min and aged . And two-step aging was also performed form . The aging behavior of the sintered composite pow-der was different from that of sintered blended powder. The peak aging time of the composite was rapid as well due to strain. Before aging, mechanical properties of sintered composite powder was significantly higher than that of sintered blended powder. These increments of properties were directly affected by ceramic particles. However, after aging, incremental rate of mechanical properties was slowed in the composite

7xxx series Al alloy has the most attractive properties including its excellent high specific strength, stress corrosion cracking and corrosion-resistance. However, in case of the Al-Zn system, the liquid phase has a transient aspect because of the high solid solubility of Zn in Al. Therefore, transient liquid phase sintering behavior was observed during the sintering process. And the amount of liquid and its duration were influenced by the process variables including heating rate and final sintering temperature. At high heating rates(), the liquid fraction increased during sintering because diffusion was minimized and therefore local saturation could easily occur. The sintered density increased with increasing heating rate.

The bi-materials composed of and its composite reinforced with SiC particles were prepared by ball-milling and subsequent sintering process. The size of powder in Al-Mg/SiCp mixture decreased with increasing ball-milling time, it was saturated above 30 h when the ball and powder was in the ratio of 30 to 1. Both powders mixture and mixture were compacted under a pressure of 350MPa and were bonded by sintering at temperatures ranging from 873K to 1173K for 1-5h. At 873k, the sound bi-mate-rials could not be obtained. In contrast, the bi-materials with the macroscopically well-bonded interface were obtained at higher temperatures than 873K. The length of well-bonded interface became longer with increasing temperature and time, indicating the improved contact in the interface between unreinforced Al-Mg part and Al-Mg/SiCp composite part. The relative density in the bi-materials increased as the sintering temperature and time increased, and the bi-materials sintered at 1173K for 5h showed the highest density.

The 6061 Al alloy based composites reinforced with 10 vol% SiC whiskers were prepared by powder metallurgy with the powders having the different sizes, i.e. < and> The composites were subjected to equal channel angular pressing (ECAP) at various conditions and the microstructural changes during ECAP were examined In the composites SiC whiskers were clustered and randomly aligned. The clusters were relatively well distributed in the composite with the smaller initial powder size. After ECAP, the clusters were aligned parallel to flow direction and became smaller. In addition, the shape of clusters was changed from irregular to round. The microstructure of the ECAPed samples were compared with those of the conventionally hot-extruded composites. The uniform microstructure and enhanced microhardness could be obtained by using the powders having the smaller size, decreasing ECAP temperature and repeating ECAP.