Research on microstructure and solidification mechanism of Al-Ti-C-Ce mother alloy prepared by titanium hydride-petroleum coke

Abstract

Microstructure of Al-Ti-C-Ce mother alloy which was prepared by titanium hydride-graphite-aluminum cerium alloy and aluminum liquid was studied by modern detection analysis methods, such as X-ray diffraction (XRD), scanning electron microscope (SEM), and energy disperse spectroscopy (EDS). Results demonstrated that the prepared Al-Ti-C-Ce mother alloy is composed of α (Al), (TiC) and (Ti2Al20Ce). Particle boundary of casting samples used the continuous eutectic structure. There are extensive distributions of coarse second-phase structures in crystals. Eutectics in the crystal boundary and the second-phase in crystals all contain Ti2Al20Ce phase. The second-phase structure of most large particles is composite structures. There are α (Al)+Ti2Al20Ce+ Al4C3+(TiC) peritectic structures with deep colors in composite particles. According to the linear analysis results, distribution of the element C is relatively uniform in the second-phase particles. C and Al contents in particles are relatively low, while Ti and Ce contents are relatively higher. Ce content in the second-phase particles is significantly higher than that in the external regions of particles. In particle regions which are covered by the second phase of composite structure, Ti and C contents are extremely higher, while Al and Ce contents are relatively lower. During the solidification process of alloy, particles containing Ti and C are precipitated firstly as crystal nucleus. The Ti2Al20Ce-containing phase realizes nucleation through particles containing Ti and C particles. αAl) realizes nucleation through the composite particles composed of Ti phase, C phase and Ce phase. The composite particles containing Ti, C and Ce precipitated firstly as the primary phase. Al-Ti-C-Ce mother alloy crystal particles are refined.