Transient Behavior of Inclusion Chemistry, Shape, and Structure in Fe-Al-Ti-O Melts: Effect of Titanium/Aluminum Ratio
Transient Behavior of Inclusion Chemistry, Shape, and Structure in Fe-Al-Ti-O Melts: Effect of Titanium/Aluminum Ratio
复制标题
DOI：
10.1007/s11663-009-9290-7
复制
发表时间：
2009-09
期刊：
影响因子：
--
通讯作者：
Congmin Wang;N. T. Nuhfer;S. Sridhar
中科院分区：
文献类型：
--
作者：
Congmin Wang;N. T. Nuhfer;S. Sridhar
在无间隙钢（IF）熔体的钢包加工过程中，如果局部钛/铝（Ti/Al）比在铝杀死后局部暂时升高，则有可能形成瞬态含钛氧化物。相稳定性图表明，当Ti/Al比增加时，al2tio5和/或液态Al-Ti- o区域变得稳定，最终在更高的Ti/Al比下，ti3o5变得稳定。在本研究中，通过改变Ti/Al比值来研究(1)在铝淬铁熔体中加入钛后夹杂物是如何演化的；(2)在足够时间后出现的夹杂物是否符合热力学预测。当Ti/Al比保持在1/4时，Al2O3是唯一的热力学稳定的氧化物，结果表明，钛加入后暂时存在瞬态含钛氧化物，但随着时间的推移，主要夹杂物为Al2O3，其形状变化不大，形成钛含量较少的瞬态夹杂物。当Ti/Al比增加到1/1时（al2o3仍然是唯一热力学稳定的氧化物），结果表明瞬态夹杂物中钛含量的增加更为明显。在这种情况下，瞬态反应伴随着从球形到不规则夹杂物的不可逆形状变化。在al2tio5稳定相区域内，当熔体Ti/Al比增加到15/1时，夹杂物群由球状为主演变为不规则夹杂；结果表明，与al2tio5化学反应相比，最终包合物的钛含量较高，而铝含量较低。透射电镜（TEM）结果表明Ti2O的存在。当熔体中Ti/Al比增大，使ti3o5成为热力学稳定的夹杂物（Ti/Al比为75/1或∞）时，加入钛后夹杂物向tiox夹杂物演化，夹杂物的形状由球形变为不规则。TEM结果表明，除了热力学稳定的Ti3O5外，还存在亚稳Ti2O，这与基于al2o3衬底的薄层钛氧化研究的结果一致。研究发现，在一定条件下，Ti2O有向热力学稳定相ti3o5转变的趋势。
During ladle processing of interstitial-free (IF) steel melts, it is possible for transient titanium-containing oxides to be formed if the local titanium/aluminum (Ti/Al) ratio is locally and temporarily increased after aluminum killing. The phase stability diagrams suggest that if the Ti/Al ratio is increased, then Al2TiO5and/or a liquid Al-Ti-O region can become stable, and eventually at even higher Ti/Al ratios, Ti3O5becomes stable. In this study, the Ti/Al ratio was successively altered to investigate (1) how the inclusions evolved after titanium addition to aluminum-killed iron melts and (2) whether the inclusions present after sufficient time were those predicted by thermodynamics. When the Ti/Al ratio was maintained at 1/4, such that Al2O3is the only thermodynamically stable oxide, the results show that transient titanium-containing oxides exist temporarily after titanium addition, but with time, the predominant inclusion was Al2O3, which would generate little shape change and produce transient stage inclusions with less titanium contents. When the Ti/Al ratio was increased to 1/1 (Al2O3still being the only thermodynamically stable oxide), the results show a more distinct increase in the titanium content of the transient inclusions. The transient reaction was, in this case, accompanied by an irreversible shape change from spherical to irregular inclusions. When the Ti/Al ratio in the melt was increased to 15/1 within the Al2TiO5stable phase region, the inclusion population evolved from spherical-dominant ones to irregular ones. It was found that the final inclusion chemistry has more titanium but less aluminum content compared with the expected from the Al2TiO5chemistry. Besides, the transmission electron microscopy (TEM) results showed the existence of Ti2O. When the Ti/Al ratio in the melt was increased such that Ti3O5is the thermodynamically stable inclusion (Ti/Al ratio of 75/1 or ∞), the inclusions evolved after titanium addition toward TiOxinclusions, which is accompanied by a shape change from spherical to irregular. The TEM results revealed and confirmed the existence of metastable Ti2O besides the thermodynamically stable Ti3O5, and it was consistent with the results based on oxidation studies of thin layers of titanium with Al2O3substrate. It was discovered that Ti2O has the tendency of transforming into the thermodynamically stable phase Ti3O5under certain conditions.