Al-Ti-C与Al-Ti-B晶粒细化剂的Zr中毒机理

摘要

通过采用扫描电镜(SEM)、能谱仪(EDS)、X射线衍射(XRD)等对Al-Ti-Zr-C与Al-Ti-Zr-B试验合金中 Al3Zr、Al3Ti、TiC或TiB2等第二相粒子结合情况的观察,研究晶粒细化剂的Zr中毒机理.结果表明:两种实验铝合金的凝固组织中Al3Zr均容易与Al3Ti结合形成聚积体,从而抑制了Al3Ti异质形核、细化晶粒的作用,出现所谓晶粒细化剂的Zr中毒现象；而TiC、TiB2粒子基本不与Al3Zr结合,但受Al3Zr的影响出现了团聚现象.根据边-边匹配晶体学模型(E2EM)计算表明:Al3Zr与Al3Ti、α-Ti具有多种可能的共格位向关系,而与TiC/TiB2粒子均只有一种可能的共格位向关系.母相-新相的共格位向关系的多少可作为晶粒细化剂设计的晶体学理论参考.%The poisoning mechanism of zirconium on the grain-refining efficiency of Al-Ti-C and Al-Ti-B based grain refiner was been studied by observing the phases distribution between Al3Zr, Al3Ti, TiC and TiB2 particles in the Al-Ti-Zr-C and/or Al-Ti-Zr-B alloys using X-ray diffraction(XRD) and scanning electron microscope (SEM) equipped with energy dispersive spectrometer (EDS). The results show that Al3Zr particles are easy to combine with Al3Ti particles both in Al-Ti-Zr-C and Al-Ti-Zr-B alloys, the potency of Al3Ti performed as nucleation centers is impaired and results in the poisoning phenomenon. While TiC and TiB2 particles seem not to integrate with Al3Zr particles though the agglomeration of TiB2 particles. The calculation results of edge-to-edge matching model (E2EM) indicate that Al3Zr has a better crystallographic matching with Al3Ti and α-Ti solute than it does with TiC and TiB2 particles, which implies the quantities of the orientation relationships (Ors) between the matrix and precipitate can be used as a crystallography theoretical consultation in designing grain refiner.