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使用有限元商业软件CALCOSOFT3D中的元胞自动机模型,对Fe-C合金凝固过程微观组织进行了模拟.形核模型采用基于高斯分布的连续性形核模型,两种形核分布函数分别处理型壁和熔体内部的形核:枝晶尖端生长速度与局部过冷度的关系采用KGT模型.计算了不同浇注温度、对流换热系数及溶液内部形核过冷度对凝固组织的影响.随着浇注温度从1778K升到1823K,晶粒密度由1.993×10~7m~(-2)减小到1.983×10~7m~(-2),晶粒平均半径从183μm增大到196.3μm;当对流换热系数由500W/(m~2·K)增加到5000W/(m~2·K),晶粒密度由2.114×10~7m~(-2)减小到1.983×10~7m~(-2),晶粒平均半径从161.2μm增大到196.3μm;随着最大形核过冷度的增大,晶粒平均半径增大,当过冷度为8,平均晶粒半径达到233.8μm. 相似文献
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Al-Si合金凝固组织的三维模拟及预测 总被引:1,自引:0,他引:1
用有限元商业软件PROCAST中的CA-FE模型,对不同工艺条件下Al-Si合金A104的凝固组织进行了三维模拟及预测,并进行了热态验证实验.研究结果表明,模拟结果与实验结果基本吻合,能够较为准确地反映出等轴晶和柱状晶的分布位置、比例和大小;当浇注温度从903K增大到993K,铸件凝固组织中柱状晶比例由22%增大到45%,且晶粒组织明显变得粗大;当冷却强度从500 W/(m2.K)增大到4000 W/(m2.K),铸件凝固组织中柱状晶比例明显增大,由14%增大到38%. 相似文献
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针对重载齿轮用18Cr2Ni4W合金钢的渗碳化学热处理过程,本研究建立了元胞自动机模型并对奥氏体的晶粒长大现象和碳化物对晶界的钉扎作用进行模拟研究。开展了18Cr2Ni4W合金钢保温实验并观察晶粒大小,发现数值模拟结果与实验观察结果具有较好的一致性。模拟和实验结果表明,随着保温时间的增加,平均晶粒尺寸增加,且温度越高,晶界迁移率越高,晶粒长大速率也越快。模拟再现了奥氏体晶粒长大过程中碳化物对晶界有钉扎作用,对碳化物阻碍晶界迁移和晶粒继续长大进行了可视化分析。本研究能够预测和再现不同渗碳温度时奥氏体晶粒尺寸的演化规律,为减少实验次数、降低渗碳工艺研发成本提供有力工具。 相似文献
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针对工业冷却水行业对抗生素类杀生剂的药效评价所采用的微生物抑菌圈直径法,提出了一种图像法测量抑菌圈直径.在获得抑菌圈图像后,首先进行灰度化和维纳滤波图像增强预处理,然后基于Hough变换提取抑菌圈图像,最后经过元胞自动机进行抑菌圈边缘检测,计算出抑菌圈直径.另外,与常规图像边缘算子(Prewitt和Canny)进行了对... 相似文献
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分别用两个元胞自动机模型对油罐底板上、下表面的点蚀生长过程进行研究。根据元胞自动机的机理和底板上、下表面的腐蚀机理,建立了元胞自动机模型的演化规则,并对底板腐蚀过程中的电化学反应和扩散过程进行了模拟。结果表明元胞自动机方法可用于油罐底板腐蚀穿孔的模拟。 相似文献
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W. J. MINFORD R. C. BRADT V. S. STUBICAN 《Journal of the American Ceramic Society》1979,62(3-4):154-154
The crystallographic features of several directionally solidified binary oxide eutectics were examined by the Buerger precession X-ray method and are discussed in terms of the lattice misfit and ionic charge compensation at the interface, particularly with regard to the oxygen sublattice. Fibrous and lamellar micro-structures are classified and the resultant morphologies related to the phase volumes. The interphase spacing proportionality to the inverse square root of the solidification rate is examined. 相似文献
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Michael L. Santella Joseph A. Horton Jong Jin Pak 《Journal of the American Ceramic Society》1990,73(6):1785-1787
Joints of high-purity Al2 O3 were made with a 56Ag-36Cu-6Sn-2Ti (wt%) experimental alloy by vacuum brazing at 900°C for 20 min. The microstructure at the ceramic-metal interfaces was examined in cross-sectional specimens of the joints, and phases formed by reaction between the braze filler metal and the Al2 O3 were analyzed for composition and crystal structure in a transmission electron microscope. A 0.1- to 0.2-μm-thick layer formed directly on the Al2 O3 surface. This layer was Ti-rich, had the face-centered-cubic crystal structure with a lattice parameter of 0.423 nm, and was identified as oxygen-deficient γ-TiO. The second reaction layer was ∼3 μm thick, and it separated the TiO layer from the metallic phases of the braze filler metal. The structure of this layer, as determined by electron diffraction, was diamond cubic of the space group Fd3m , with a lattice parameter of 1.137 nm. The combination of microanalysis and diffraction data confirmed that this phase was Ti3 (Cu0.76 Al0.18 Sn0.06 )3 O and indicated that it can be classified as an n phase. 相似文献