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Ni 을 함유하는 Hadfield 강의 탄화물석출에 관하여 (3) : 냉간가공의 영향 Effect of Cold working
김문일,김재묵,강대석 대한금속재료학회(대한금속학회) 1977 대한금속·재료학회지 Vol.15 No.1
바나듐(V)을 含有하는 modified hadfield steel을 冷間加工한 後 再加熱하여 炭化物과 pearlitic constituents의 恒溫析出線圖를 作成하였고 析出物의 形態 및 種類에 따르는 硬度變化를 調査檢討하였다. 여기서 얻은 結果를 要約하면 다음과 같다. 1) 炭化物 및 pearlitic constituents析出은 冷間加工에 依해서 현저히 促進된다. 2) 炭化物析出은 270∼940℃의 溫度範圍에서 일어나며 500∼850℃에서 가장 빨리 일어난다. 한편 pearlitic constituents는 380∼760℃의 溫度範圍에서 析出되며 約 650℃附近에서 가장 빨리 析出된다. 3) 炭化物析出은 300∼400℃의 低溫區域에서는 slip line을 따라서 優先的으로 일어나며 그 後 溫度가 上昇하고 加熱時間이 길어짐에 따라서 粒界와 slip line에서 同時에 일어난다. 4) 550℃에서 100時間加熱하였을 때 最高硬度値(Hv 470)가 얻어지며 pearlitic constituents보다는 粒內析出物이 硬度增加에 크게 寄興하는 것으로 推定된다. A thorough examination has been carried out on the change of microstructure and hardness of cold-worked modified Hadfield steel by isothermal heating, from which the following conclusions could be drawn. 1) Precipitation of the carbide and pearlitic constituents was promoted considerably by cold-working. 2) Carbide precipitation occurred, when cold-worked modified Hadfield steel was reheated, in the temperature range between 270 and 940℃. This precipitation took place most rapidly between 500 and 850℃. Formation of pearlitic constituents was restricted to the temperature range 380-760℃, and was the most rapid in the vicinity of 650℃. 3) Formation of the carbide was preferentially preceded on the slip line in the lower temperature range, but with the increase in temperature and heating time, it was found both on the grain boundary, and slip line. On further increase in temperature, the carbide was spheroidized. 4) Increased amounts of transformation products led to higher hardness with a maximum of about Hv 470 obtained on heating at 550℃ for 100 hours. A more effective hardner contributing to the maximum hardness appeared to be acicular carbide rather than pearlitic constituents.
Hg-annealing 온도가 LPE 법으로 성장시킨 Hg0.8Cd0.2Te 의 전기적 특성에 미치는 영향
김재묵,서상희,문성욱,최종술,정용택 대한금속재료학회(대한금속학회) 1990 대한금속·재료학회지 Vol.28 No.6
Hg_(0.8)Cd_(0.2)Te epitaxial layers were grown by an LPE(liquid phase epitaxy) process. As-grown Hg_(0.8)Cd_(0.2)Te showed p-type conductivity with a carrier concentration of 8.8×10^(17)㎝^(-3). Annealings of as-grown Hg_(0.8)Cd_(0.2)Te wafers in Hg-atmosphere were performed over the temperature range 200 to 430℃. Annealings below 300℃ resulted in n-type conductivity with carrier concentrations from 10^14 to 10^15 cm^-3 and showed a maximum value at about 260℃. p→in type conversion temperature is thought to be determined by Hg-interstitials rather than residual donor impurities. The phase boundary of Hg_(0.8)Cd_(0.2)Te on the metal-rich side could be obtained.
(111) CdTe 기판의 이탈방위각이 LPE 법으로 성장시킨 Hg0.7Cd0.3Te 박막의 표면 형상에 미치는 영향
김재묵,서상희,임성욱,최인훈,곽로정 대한금속재료학회(대한금속학회) 1991 대한금속·재료학회지 Vol.29 No.1
Hg_(0.7)Cd_(0.3)Te epilayers were grown by a silder-type LPE(liquid phase epitaxy) technique using Te-rich growth solution. CdTe substrates of (111)Cd orientation with various degrees of misorientation were prepared by vertical Bridgman crystal growth and subsequent chemo-mechanical polishing processes. Epi-layers, which were grown using a substrate with 1^0 misoriented toward four different directions, showed a typical terrace morphology with terrace fronts perpendicular to the misorientation directions. As the misoriented angle increases, the terrace width decreases, while the terrace height increases. With the misorientation larger than 2^0, the terrace structure begins to disappear transforming into a wave-like surface. The initial stage of the epi-layer growth is thought to be governed by the so-called step bunching process. Dislocations begin to play a major role in the growth process when the terrace becomes as wide as 10 to 30㎛. Epi-layers were examined by Nomarski differential interference contrast optical microscope and stylus
Hgo07Cd0.3Te 박막의 LPE 성장시 성장시간에 따른 표면형상의 변화
김재묵,송원준,서상희,임성욱,최인훈,문성욱 대한금속재료학회(대한금속학회) 1990 대한금속·재료학회지 Vol.28 No.2
HgCdTe is the most widely used material for infrared photodetectors. HgCdTe epi-layers were grown on CdTe substrates with (111) orientation, using a slider LPE(Liquid Phase Epitaxy) technique. The change of surface morphology during LPE growth of Hg_(0.7)Cd_(0.3)Te was investigated. The wave-like surface at the initial stage of growth has transformed gradually to the terrace-like surface and the terrace width has increased with increasing growth time. Infrared tansmission was used to determine the composition of HgCdTe epi-layers.
Ni 을 함유하는 Hadfield 강의 탄화물 석출에 관하여 (1)
김문일,성장현,김재묵 대한금속재료학회(대한금속학회) 1975 대한금속·재료학회지 Vol.13 No.4
Hadfield 鋼에 Ni을 3.5% 添加하여 炭化物과 pearlitic constituents의 析出線圖와 析出物의 形態 및 硬度에 미치는 組織變化를 調査하였으며 아울러 Ni에 依한 析出의 影響도 比較 檢討하였다. 여기서 얻은 結果를 要約하면 다음과 같다. 1) Hadfield鋼에 Ni을 添加하면 炭化物析出 溫度區間은 좁아지며, pearlitic constituents의 析出溫度區間은 거의 變化하지 않는다. 2) 炭化物新出은 670∼700℃에서 가장 빠르며 pearlitic constituents의 析出은 600℃에서 가장 빨리 일어난다. 3) 炭化物析出은 低溫區域을 除外하고는 먼저 粒界에 film狀의 炭化物이 形成되며, 加熱時間이 길어지고 溫度가 上昇함에 따라 針狀炭化物, 粒狀炭化物, chain狀의 炭化物이 形成된다. 4) 針狀炭化物보다 pearlitic constituents가 硬度增加에 크게 寄與하는 것으로 推定된다. 5) 炭素量의 增加에 따라 pearlitic constituents의 析出開始時間이 빨라지며, 이 現象은 Ni添加에 依해 더욱 促進된다. The effects of Ni addition on the precipitation of carbides and pearlitic constituents in Hadfield steel were investigated by means of microscopy and hardness measurements. From this experiment the following results were obtained. 1) By the addition of Ni, the temperature range of precipitation of carbides became narrow, but that of pearlitic constituents was nearly unchanged. 2) Carbides were precipitated preferentially in the range of 600-700℃ and pearlitic constituents at 600℃. 3) Except the lower temperature range, carbides were precipitated in the shape of film at the grain boundaries in the earlier heating stage, but with the increase in heating time and temperature, the shape of carbides was changed as follows; acicular, granular and chain-like carbides. 4) Increased hardness was mainly affected by pearlitic constituents precipitation rather than acicular carbides. 5) With the increase in carbon contents, the pearlitic constituents precipitation rate was accelerated remarkably by the addition of Ni in Hadfield steel.
수직 Bridgman 법에 의한 CdTe 단결정 성장시 성장속도가 전위 밀도와 분포에 미치는 영향
김재묵,송원준,서상희,임성욱,최인훈 대한금속재료학회(대한금속학회) 1988 대한금속·재료학회지 Vol.26 No.8
CdTe single crystals were grown by a vertical Bridgman method. The growth rate was varied between 1.1 and 5.4 ㎜/hr with maintaining the temperature gradient of 16℃/㎝ at the solid-liquid interface. Etch-pit structures of CdTe single crystals were investigated. The dislocation density was larger and the subgrain size was smaller at the surface and bottom of the crystal. With the increasing growth rate, the dislocation density gets larger and the subgrain size becomes smaller The thermal stress, which is supposed to build up during the solidification process, can explain our results.