掺V和Ag的TiAl合金中缺陷和电子密度的正电子湮没研究

Study of Defects and Electron Densities in TiAl Alloy Doped with V and Ag by Positron Annihilation

摘要:

测量了Ti50Al50，Ti50Al48V2，Ti50Al48Ag2合金和充分退火的Ti，Al，Ag，V金属的正电子寿命谱，利用正电子寿命参数分别计算了合金基体和缺陷态的自由电子密度。TiAl合金的脆性与其基体和晶界缺陷处的自由电子密度较低有关。在富Ti的TiAl合金中加入V，V原子比Al和Ti原子能提供较多的自由电子参与形成金属键，因而提高了合金基体和晶界缺陷处的自由电子密度；在TiAl合金中加入Ag也有类似的效应。在TiAl合金中加入V和Ag，有利于提高合金的韧性。

Abstract:

Positron lifetime spectra of Ti50Al50, Ti50Al48V2, Ti50Al48Ag2 alloys and annealed Ti, Al, Ag, V metals were measured. The electron densities in the bulk and defects of the alloys were calculated by positron lifetime parameters. The poor ductility of binary TiAI alloy is related to low free electron densities in the bulk and the grain boundaries of the alloy. When V are added into Ti-rich TiAI alloy, V atoms will provide more free electrons than both Al and Ti atoms to participate in metallic bonds, thus increasing the electron densities in the bulk and the grain boundary simultaneously. Ag additions appear to have an effect similar to V additions. Both V and Ag are benefit elements in enhancing the ductility of TiAl alloys.