Mo离子注入钢退火过程中的相变研究

着重研究了金属离子注入合成表面优化复合层的机理和纳米相镶嵌结构形成,探索了注入和退火过程中纳米结构和相变过程,讨论相变机制.实验中发现用较低束流密度的Mo离子注入钢明显地改变了钢表面的结构,可使钢表面晶粒细化,使阻止位错移动的晶界数量增多;可在钢表面形成Mo原子超饱和固溶体;随所用的束流密度的增加,注入时表面温度升高,注入的Mo原子将与钢中的铁原子和碳原子化合而形成纳米尺寸的析出相.这些弥散的析出相在钢表面形成了弥散强化.用低束流密度注入后经过退火,在钢表面也形成了纳米尺寸的析出相,从而增加了表面弥散强化的效果.随退火温度的增高,纳米析出相将会聚成大一些的纳米颗粒,颗粒之间互相连接而形成网状结构,这将会进一步增加表面强化效果.

A STUDY ON PHASE TRANSITION IN Mo IMPLANTED STEEL DURING ANNEALING

The synthesis of optimum complex layer and nanophases embedded structure are studied. The phase transition in Mo implanted steel is observed during thermal annealing. The mechanism of phase transition is discussed. When lower Mo ion flux is used, the surface structure is changed obviously, the crystal gains are fined, the amount of grain boundaries against dislocation movement increases. Saturation solid state in the implanted layer is established. The strengthening of saturation solid state is formed. The target temperature rises when ion flux increases. So that the phases of Fe and Mo atoms are precipitated, The phases at nano meter scale are observed. The dispersed phase strengthening is established. When the sample is implanted with low ion flux and then annealed, the phases at nano meter scale appears, and dispersed phase strengthening is formed also. When the annealing temperature increases, the size of precipitated phases is increased. A net structure is formed by the precipitated phases. The effects of strengthening are enhanced further.