Recrystallization - Recrystallization

Japanese: 再結晶 - さいけっしょう（英語表記）recrystallization

(1) A method for increasing the purity of a crystalline substance by utilizing differences in solubility. When a substance is dissolved in a solvent under appropriate conditions, and the temperature is lowered or the solvent is evaporated to a level above the saturation concentration of the desired substance, crystals of higher purity than the original crystals may precipitate.
(2) The phenomenon in which crystals of a certain mineral grow in a rock while it is exposed to weather and then react with different minerals or foreign substances, resulting in a rock that is different from the original.
(3) Processed metal crystals have various lattice defects and the associated internal strain. When they are heated, the strain energy is converted into atomic kinetic energy for atomic rearrangement, and new crystal nuclei are formed. They grow while incorporating the original crystal grains, and the structure is replaced by a new, strain-free crystal grain structure. This is called recrystallization (or primary recrystallization). The greater the amount of deformation caused by processing, the lower the temperature at which recrystallization occurs, and the more new nuclei are generated, making the recrystallized structure finer. The material exhibits good mechanical properties, so this is used for tempering by forging or rolling. Conversely, if the amount of processing is small, the recrystallization temperature is high, the number of nuclei is small, and the recrystallized structure is coarse. This is used to create single crystals. The recrystallization temperature is usually the lowest recrystallization temperature when the degree of processing is sufficiently large. The phenomenon in which a small number of crystal grains selectively grow after the completion of primary recrystallization, driven by the release of grain boundary energy, is called secondary recrystallization. (→Recovery)

Source: Encyclopaedia Britannica Concise Encyclopedia About Encyclopaedia Britannica Concise Encyclopedia Information

Japanese:

(1) 溶解度の差を利用して結晶性の物質の純度を上げる方法の1つ。適当な条件で溶媒に物質を溶かし，温度を下げたり，溶媒を蒸発させたりして，目的とする物質の飽和濃度以上にすると初めの結晶よりも純度の高い結晶が析出する場合がある。
(2) 岩石が風雨にさらされている間に岩石中のある鉱物の結晶が成長し，それが異種鉱物または外来物質と反応し，初めと異なった岩石を生じる現象。
(3) 加工された金属結晶は種々の格子欠陥とそれに伴う内部ひずみをもつが，これを加熱するとひずみエネルギーは原子再配列のための原子運動エネルギーに転化し，新しい方位の結晶核ができて，もとの結晶粒を取込みながら成長し，組織は新しい無歪の結晶粒組織に交代する。これを再結晶 (または一次再結晶) という。加工変形量が大きいほど再結晶は低温で起り，新核発生数も多くなって再結晶組織は微細になり，材料は良好な機械的性質を示すので，これを利用して鍛造や圧延による調質が行われる。逆に加工量が小さいと再結晶温度は高くなり，核発生数は少く，再結晶組織は粗大になる。これは単結晶作製に利用される。通常再結晶温度というのは，加工度が十分大きいときの最低再結晶温度である。また一次再結晶終了後に粒界エネルギーの解放を駆動力として少数の結晶粒が選択的に成長する現象を二次再結晶という。 (→回復 )

出典　ブリタニカ国際大百科事典小項目事典ブリタニカ国際大百科事典小項目事典について　情報

<<: Psychedelic - psychedelic

>>: Judgment - Decision