离子渗氮层中γ′-Fe_4N相内位错环和层错类型的研究

Study on Dislocation Loop and Stack Fault in Plasma-nitrided Layer by Rare-earth Catalytic Penetration

用透射电镜衍衬方法测定了稀土催渗离子渗氮层中γ'-Fe_4N相内位错环及层错的类型。结果表明,位错环为b=1/3[111]空位型,其形成原因是:在离子渗氮过程中,高能离子的持续轰击导致大量空位点缺陷的产生,随后空位聚集成空位片,最终崩塌形成位错环;而层错类型为抽出型,其两边的不全位错是1/6(112)型Shockley不全位错,它们是由全位错1/2[110]=1/6[121]+1/6[211]反应分解形成的。

The dislocation in γ' -Fe4N phase in the plasma-nitrided layer and the imperfect dislocations on either side of the stack faults have been analyzed and determined by TEM diffraction contrast method. The results show that the dislocation loops with b=1/3[111] are vacancytyped, the forming reason is that during the pro-cess of plasma nitriding the continuous bombardment of high energy to the formation of a great many point defects-vacancies, go on vacancy flakes are formed by gathering many vacancies, and finally collapse and develop dislocation loops. However, stack faults are vacancy-typed, the imperfect dislocations on either side of stackfaults are a type of shocklay imperfect dislocations with Burgers vector b= 1/6< 112 >, which is formed by reactiondecoposition of per perfect dislocations with Burgers vector 1/2[110] = 1/6[121]+ 1/6[211].