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采用真空感应磁悬浮熔炼合金、重力浇注入室温石墨模具的方法,分别制备了Ti-47Al-2Cr-2Nb,Ti-47Al-2Cr-2Nb-0.8B和Ti-47Al-2Cr-2Nb-0.1C 3种名义成分的铸锭.对铸锭进行成分分析并利用体视显微镜和扫描电子显微镜对铸锭的铸造收缩缺陷和组织进行分析.结果表明:Ti-47Al-2Cr-2Nb合金铸锭有很强的柱状晶生长趋势,在轴线附近区域形成分散的缩松;加入0.8%B(原子分数)后,铸锭的组织得到细化,并削弱了柱状晶生长趋势,收缩缺陷分布集中以大缩孔方式存在,显微缩松的密度和尺寸均降低.添加0.1%C(原子分数)后,铸锭的组织和缩孔缩松与Ti-47Al-2Cr-2Nb比均无明显变化.
Ti-47Al-2Cr-2Nb, Ti-47Al-2Cr-2Nb-0.8B and Ti-47Al-2Cr-2Nb-0.1C were prepared by vacuum induction magnetic levitation melting of alloy and gravity casting into room temperature graphite mold. Nominal composition of the ingot.Analysis of ingot components and the use of stereomicroscope and scanning electron microscopy casting shrinkage defects and microstructure analysis.The results show that: Ti-47Al-2Cr-2Nb alloy ingot has a strong The growth trend of columnar crystals formed dispersion shrinkage in the vicinity of the axis. After addition of 0.8% B (atomic fraction), the microstructure of the ingot was refined and the growth trend of columnar grains was weakened. The distribution of shrinkage defects concentrated in the way of shrinkage shrinkage The density and the size of the micro-shrinkage decreased, and the addition of 0.1% C (atomic fraction) showed no significant change in the structure of the ingot and the shrinkage of shrinkage cavity compared with Ti-47Al-2Cr-2Nb.