Cu—Zn—Al合金热循环相变的电镜观察

TEM Observation of Transformation in Situ During Thermal Cycling in a Cu-Zn-Al Alloy

利用电镜高温台,直接观察Cu-Zn-Al合金在热循环过程中电子衍衬及电子衍射像的动态变化。低温马氏体M18R呈板条状,内部有厚度为5～10nm的层错亚结构。在热循环中,衍衬像不发生明显改变,但观察到可逆的电子衍射图变化,分析表明这是可逆的DO_3M18R型相变。在母相向马氏体转变之前,还出现“预马氏体效应”特征的漫散射条纹和额外衍射斑点。

By using a heating stage, the dynamic change of EDP(electron diffractionpattern) and EM (electron micrograph) was observed in situ during thermal cyc-ling in a Cu-Zn-Al alloy. At room temperature, lathed martensite belongs to M18Rin structure and consists of parallel stacking fault substructure with 5～10 nm inthickness. During thermal cycling, no obvious change of EM was observed but areversible change of EDP was, which is shown to correspond to reversible DO_3-M18R transformation. Before martensite transition, the diffuse scattering streaksand extra reflection spots, which are the characteristics of premartensite effect,were also occurred.