Various kinds of Mg-Zn-Ca base alloys were rapidly quenched via melt spinning process. The meltspun ternary and quaternary alloy ribbons were heat-treated, and then the effects of additional elements on age hardening behavior and phase change of precipitates were investigated using Vickers hardness tester, XRD, and TEM equipped with EDS system. In ternary alloys, age hardening was mostly due to the distribution of and . The stable phases of precipitates were varied according to the aging temperature and the alloy composition. With the increase of Ca content, precipitates were detected more than precipitates. In quaternary alloys, the precipitates taken from Mg-Zn-Ca-Co were identified as new quaternary phase, whereas those taken from Mg-Zn-Ca-Zr as MgZnCa containing Zr. In general, the ternary alloy showed higher peak hardness and thermal stability than the quaternary considering the total amounts of the solutes. It implies that the structure of precipitate should be controlled to have the coherent interface with the Mg matrix.

In order to fabricate complex-shaped polycrystalline ceramics by sintering, organic binders are usually pre-mixed with ceramic powders to enhance the formability during the shape forming process. These organic binders, however, must be eliminated before sintering so as to eliminate the possibilities of poor densification and unusual grain growth during sintering. The present work studies the effect of binder addition on grain growth behavior during sintering of piezoelectric ceramics. The microstructures of the sintered samples were examined for various heating profiles and debinding schedules of the binder removal process. Addition of Polyvinyl butyral(PVB) binder promoted abnormal grain growth especially in incompletely debinded regions. Residual carbon appears to change the grain shape from comer-rounded to faceted and enhance abnormal grain growth

Mg의 시비농도를 인위적으로 조절한 후 국화를 재배하면서 각 원소의 시비수준이 생육과 절화 품질에 미치는 영향을 구명하고 생육을 우수하게 유지할 수 있는 식물체 및 토양의 한계농도를 밝히기 위하여 수행하였다. Mg 결핍증상은 노엽의 엽맥이 갈변한 후엽 전체로 갈변 현상이 확산되고, 최종적으로 노엽이 탈락하는 특징을 나타내었다 Mg 시비농도가 증가할 수록 정식 109일 후의 절화중이 무거워져 1.5mM 시비 구에서 8.84g이었다. 건물 중은 Mg 시비농도가 증가함에 따라 건물중도 증가하였으나, 2.0mM 이상의 고농도 시비구에서는 오히려 감소하였다. 0.5, 1.0 및 1.5mM 시비구에서의 건물중이 8.42, 8.75 및 8.84g이었고, 최근에 완전히 전개된 잎의 Mg함량이 각각 0.34, 0.53 및 0.71%였다. 따라서 절화국 'Biarritz'의 품질을 우수하게 유지하기 위해서는 가장 최근에 완전히 전개된 잎(최상위에서 3~4번째 잎)의 건물중을 기준으로 0.64% 이상이 유지되도록 시비해야 하며, 건물중이 가장 무거웠던 1.5mM의 토양 용액내 농도를 고려할 때 3.68mg·L-1 이상의 Mg 농도가 되도록 시비하여야 한다.

Ultrafine titanium carbide particles were synthesized by the reaction of liquid-magnesium and vaporized TiCl+CCl(x = 1 and 2) solution. Fine titanium carbide particles with about 50 nm were successfully produced by combining Ti and C atoms released by chloride reduction of magnesium, and vacuum was then used to remove the residual phases of MgCl and excess Mg. Small amounts of impurities such as O, Fe, Mg and Cl were detected in the product, but such problem can be solved by more precise process control. The lattice parameter of the product was 0.43267 nm, near the standard value. With respect to the reaction kinetics, the activation energy for the reactions of TiCl+CCland Mg was found to 69 kJ/mole, which was about half value against the use of TiCl+CCl, and such higher reactivity of the former contributed to increase the stoichiometry until the level of TiC and decrease the free carbon content below 0.3 wt.%.