http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
Practical Application of Diffusion Pathway Analysis for SiC-Metal Reactions
( J. S. Park ),( J. Cho ),( S. Yi ),( J. H. Perepezko ) 대한금속재료학회 ( 구 대한금속학회 ) 2006 METALS AND MATERIALS International Vol.12 No.3
Diffusion pathway analyses and operation kinetics for SiC-/metal interface reaction have been investigated. To select the materials for an interlayer between an SiC and Ni reaction couple, a constructed chemical potential diagram has been utilized. When Cr was selected as the interlayer material for the SiC/Ni diffusion couple, the reaction pathway and product phase morphology have been modified by controlling the component flux. The strategy of modifying the diffusion pathway provides insight for achieving a stable interface design and for controlling the interface morphology within a kinetic bound.
Strategies for Designing Composite Materials for High Temperature Application
Park, J . S .,Perepezko, J . H . 대한금속재료학회(대한금속학회) 1999 METALS AND MATERIALS International Vol.5 No.6
A clear understanding of the factors controlling reproducible composite processing is critical for high temperature application. One approach to obtain stable phase combinations (i.e. compatibility) is to use a controlled interface reaction (in-situ layer design). An effective approach to control the reaction products and diffusion pathway by adding an extra component layer has been practiced and analyzed based upon the relative component fluxes. At the same time, the observed diffusion pathway has been examined in terms of a chemical potential framework, which can provide in assistance interpreting kinetic data in multicomponent systems. While component chemical potential values can increase and decrease through the interdiffusion reaction layers, the total free energy value will be decreased during the interdiffusion reaction. In order to examine the operating principles involved in the synthesis of in-situ composites, model ternary systems including potential materials such as TiAl and SiC have been investigated.
백종승,강춘식,Loper, C. R.,Perepezko, J. H. 대한금속재료학회(대한금속학회) 1982 대한금속·재료학회지 Vol.20 No.11
熔融狀態의 合金을 急冷(10^6℃/sec)方法을 利用하여 凝固시킬때 자주 觀察되는 非平衡狀態의 獨特한 顯微鑛組織은 高度의 過冷却現象이 結晶質의 核生成過程에서 關係되였음을 나타낸다. 따라서 過冷却現象이 高速凝固過程에 미치는 基本過程을 硏究하기 爲한 Model approach로 徐冷條件 (10∼30℃/min)에서도 高度의 過冷却現象 (0.3∼0.4 Tm)을 얻을 수 있는 Droplet Emulsion Technique이 低融點金屬에 導入되었다. Droplet Emulsion Technique의 應用은 高度의 過冷却狀態에서 작은 droplet를 (10∼20μ)을 빠른 速度로 凝固시켰을때, 急冷方法을 使用했을 때와 같은 準平衡相들의 形成이 可能함을 보여 줄 뿐만 아니라 이러한 準平衡相들의 核生成過程을 組織的으로 檢討할 수 있는 初期 固溶體를 觸媒로 한 非均一核生成實驗을 可能케 해 주었다. 이러한 實驗結果에 따라 金屬粉末裝置에 高速凝固方法이 應用된다면 粒子精製(grain refinement) 效果뿐만 아니라 核生成過程에서 顯微鏡組織의 發達을 調節함으로써 顯微鏡組織의 形態變形이 可能하여 優秀한 物理的性質을 갖인 새로운 金屬材料의 開發이 可能함이 밝혀졌다. 더 나가서, droplet方法에 依한 液體金屬의 過冷却實驗은 高速凝固過程 뿐 아니라 在來式 鑄物方法에서 일어나는 凝固過程을 糾明하는데에도 基凝的인 資料가 된다고 믿어 진다. A droplet emulsion technique which allows a deep undercooling (0.3-0.4Tm) at slow cooling rate (10-30℃/min) has been applied as a model approach to study the basic solidification mechanisms associated with rapid solidification processing. When a liquid metal is undercooled substantially, the crystal growth following nucleation will be rapid regardless of the cooling rate. Often, the usual solidification reactions can be suppressed at high undercooling by the formation of metastable solid solutions, intermediate phases and in some cases amorphous solids. The kinetic phase selection mechanism has been examined by a controlled nucleation catalysis experiment in which the primary solid solution is established as one type of suitable catalytic site for the generation of metastable phases during nucleation. Phase selection promoted by undercooling and known nucleation catalysis reactions provides numerous possibilities for nucleation controlled structure modification. This indicates that rapid solidification powder processing not only has a valuable potential for grain refinement, but also has extensive possibilities for microstructural modification.