Andreia Sommerfeld
,
Bernd Bö
,
ttger
,
Babette Tonn
材料科学技术（英文）
Microstructure strongly influences the mechanical properties of cast iron. By inoculating the melt with proper inoculants, foreign substrates are brought into the melt and eventually the graphite can crystallize on them. The elements and substrates that really play a role for nucleation are yet unknown. Until now there is very little knowledge about the fundamentals of nucleation, such as composition and morphology of nuclei[1,2]. In this work we utilized EN-GJL-200 as a base material and examined several produced specimens. The specimens were cast with and without inoculants and quenched at different solidification states. Specimens were also examined with a high and low oxygen concentration, but the results showed that different oxygen contents have no influence on the nucleation in cast iron melts. Our research was focused on the microscopic examination and phase-field simulations. For studying the samples we applied different analytical methods, where SEM-EDS, -WDS were proved to be most effective. The simulations were conducted by using the software MICRESS®[3], which is based on a multiphase-field model and has been coupled directly to the TCFE3 thermodynamic database from TCAB. On the basis of the experimental investigations a nucleation mechanism is proposed, which claims MnS precipitates as the preferred site for graphite nucleation. This theory is supported by the results of the phase-field simulations.
关键词:
Graphite nucleation
,
null
,
null
,
null
刘志勇
,
许庆彦
,
柳百成
金属学报
针对工程上应用广泛的AZ91D压铸镁合金, 建立了其凝固过程中微观组织演化的数学物理模型. 采用改进的三维微观元胞自动机(CA)模型, 耦合三维溶质场计算,结合压铸镁合金进行了微观组织模拟. 模拟结果再现了在多晶粒同时生长的情况下,初生晶间的溶质扩散、溶质富集直至共晶转变的全部演化过程. 应用此模型模拟了实际AZ91D压铸件不同部位的微观组织, 模拟结果与金相观察结果符合较好.
关键词:
镁合金
,
Solute concentration field
,
Magnesium alloy
,
Die casting
