propagation of dislocations 中文意思是什麼
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The micromechanisms of fracture in engineering materials have been studied in this thesis, with particular emphasis on the dislocations behavior in the front of crack tip and the processes of crack nucleation and propagation on nanometer scale. the relation between the microprocesses of fracture and the macromechanical behaviors were investigated, which will be helpful to the strengthening and toughening of engineering materials
本文首先對材料斷裂文獻進行綜述，了解斷裂微觀機理研究的過去成就、現狀和發展，確定本文研究的內容為工程材料斷裂的微觀機理，側重裂尖微區位錯行為和納米尺度上微裂紋形核與擴展過程及微觀組織的影響，斷裂微觀過程與宏觀力學行為的關系，為工程材料的強韌化提供理論依據。 -
It was found that many dislocations were emitted from the crack tip during the early stage of crack propagation and were driven out of the crack tip area, and them piled up inversely. a closed dislocation free zone ( dfz ) was formed between the crack tip and the pile - up dislocations. keeping displacement constant, the dislocations were still emitted from the crack tip for a while
本文首先系統地研究了工業純金屬（ fe ， al ， ti和mg ）斷裂的微觀過程，發現所研究的工業純金屬斷裂過程裂尖均首先發射位錯，並離開裂尖向前運動、在裂尖留下無位錯區，位錯反塞積在五位錯區的端部，反塞積位錯群一般呈封閉狀包圍無位錯區。 -
The width of stacking fault increased as partial dislocations move forward. in the fracture of 18 - 8 stainless steel, many dislocations were emitted from the crack tip during the early stage of crack propagation and moved forward, and then a dfz was formed between the crack tip and the pile - up dislocations. the dfz is an elastic zone
不銹鋼斷裂時，裂尖首先發射位錯，並離開裂尖向前運動，裂尖前方留下無位錯區，位錯反塞積在無位錯區的端部，無位錯區是應變很高的異常彈性區，隨著裂紋的擴展，無位錯區逐漸發生晶體碎化和轉動。 -
Keeping displacement constant, the length of dfz decreased. the less the lattice resistance is, the longer the dfz is. during the crack propagation, the pile - up dislocations may move forward in the previous direction or in another direction which caused shape of dfz changed. the dislocations emitted from the crack tip might pile up in the dfz and can be served as dislocation source in the successive loading
在裂紋擴展過程，反塞積位錯群發生變化，可以沿原來方向繼續向前運動，也可能改變運動方向使無位錯區的形狀發生變化，后來發射出的位錯可以在原五位錯區中塞積，並可作為位錯源在後續的加載中發射位錯。 -
The less the lattice friction is, the longer time the dislocated emission keeps. the size of dfz and the morphology of pile - up dislocations would change during the crack propagation. the length of dfz increased as applied stress increased
在保持恆位移過程中，裂尖位錯發射與運動還會持續進行一段時間，位錯運動的點陣阻力越小，位錯發射與運動持續的時間越長。
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