Zr-Nb合金调幅分解组织的研究

Spinodal Decomposition Microstructure in Zr-Nb Alloys

首先借助文献中报道的Zr-Nb合金体系中bcc相的热力学参数计算了Zr-Nb相图中处于混溶间隙内部的锆铌合金发生调幅分解的温度以及成分区间,然后通过X射线衍射(XRD)、扫描电子显微镜(SEM)、透射电子显微镜(TEM)等实验方法对部分成分的Zr-Nb合金进行验证。在实验过程中,首先不同成分锆铌合金均需在β单相区保温进行固溶处理,得到单一的bcc相,然后在预测的调幅分解温度下进行时效处理。研究结果表明,Zr-0.35Nb,Zr-0.4Nb和Zr-0.45Nb合金在不同温度下保温时,均在保温初期发生了调幅分解,表明调幅分解发生在相变初期;调幅分解温度越高,转变发生越迅速;调幅分解首先发生在晶界处,并逐渐向晶内转变;得到的组织与预测的调幅分解组织吻合较好。

The spinodal decomposition temperature and composition range of zirconium-niobium alloy were firstly calculated through thermodynamic data of bcc phase reported in the literature of Zr-Nb alloy system. Subsequently, the microstrueture of different compo- sitions of Zr-Nb alloys was validated by X-ray diffraction （XRD） , scanning electron microscopy（SEM） , transmission electron micros- copy （TEM） etc. During the experiments, different compositions Zr-Nb alloys were heated in β phase region firstly to acquire a single bcc phase, and then aged at spinodal decomposition temperature determined by previous calculation. The results showed that the spi- nodal decomposition occurred in early heating time when Zr-0.35Nb, Zr-0.4Nb and Zr-0.45Nb alloys were heated at different tempera- tures, which indicated that the spinodal decomposition occurred at the early stage of transformation; when the spinodal decomposition temperature was higher, the transformation occurred more rapidly; spinoda] decomposition firstly occurred at grain boundaries, and gradually transformed into the grain inside; the predicted spinodal decomposition microstrueture was obtained when the samples were treated at the calculated spinodal decomposition temperatures and compositions ranges.