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在用正电子湮没方法研究金属合金的塑性变形时,一般说,于初始变形阶段,正电子湮没参数随变形量增长而增大,当大到一定程度下,正电子湮没参数呈现饱和趋势。但也有例外,如Cu-Zn-Al形状记忆合金便会出现与上述规律不同的异常现象,即马氏体Cu-Zn-Al合金冷轧变形量在5％左右时,其正电子S参数基本是不变的,或者说缺陷无增殖现象。与此现象可能相关的原因是初期的变形机制主要属马氏体片的自协作机制而不是一般的滑移机制。
When using positron annihilation method to study the plastic deformation of metal alloys, it is generally said that in the initial deformation stage, the positron annihilation parameter increases with the increase of deformation, and when it reaches a certain degree, positron annihilation parameters show a tendency of saturation. However, there are some exceptions. For example, the Cu-Zn-Al shape memory alloy will exhibit anomalous phenomena different from those described above. When the amount of cold deformation of the martensite Cu-Zn-Al alloy is about 5%, the positron-positive S parameters Is the same, or that there is no proliferation of defects. This phenomenon may be related to the reason that the initial deformation mechanism is mainly the self-cooperation mechanism of the martensite sheet rather than the general slip mechanism.