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Zr基大块非晶合金连续成型的凝固过程数值模拟
Numerical Simulation of Zr-based Bulk Amorphous Alloys during Continuous Casting Solidification Process
【作者】 马月姣；
【导师】 贾非；
【作者基本信息】 大连理工大学 ， 材料加工工程， 2012， 硕士
【摘要】 大块非晶合金材料,因其结构特征独特,而具有许多优异的性能,有着良好的应用前景。大块非晶合金的制备是其广泛应用的一个重要方面,因此研究低成本、高效率的大块非晶合金连续制备技术具有重要的现实意义。本文总结了非晶合金凝固过程数值模拟的研究成果及动态。对铜模铸造法制备Zr基大块非晶合金的凝固过程进行了模拟计算,通过计算结果与实测结果的对比,验证模型的准确程度。并通过计算,分析了大块非晶合金热物性参数的选值对模拟结果的影响,优化了铜模铸型的尺寸。在对铜模铸造法制备大块非晶合金的凝固过程模拟研究基础上,结合课题组已有成果,对Zr48Cu36Ag8A18大块非晶合金连续成型的凝固过程进行模拟研究。针对自主研发的连铸设备本身特点,推导了复合铸型内的热流密度的计算公式。分析了非晶合金熔体的凝固特性以及Zr基非晶合金热物性参数随温度的变化规律。建立了二维连铸坯温度场有限元模型,确定了初始条件和边界条件,利用ANSYS大型有限元通用分析软件对Zr48Cu36Ag8Al8大块非晶合金连续成型的温度场进行了模拟计算,得到了连铸过程中铸坯的温度场及各主要节点温度随时间的变化曲线。Zr48Cu36Ag8Al8大块非晶合金连铸过程温度场的模拟计算结果表明：在复合铸型中,水冷铜模对合金熔体起主要冷却作用,石墨铸型内合金熔体温度变化较小；在连铸工艺参数中,浇注温度、冷却水流量、拉坯速率等参数的改变均对铸坯的温度分布和最终结构产生影响。通过工艺参数的优化,使铸件达到非晶合金的形成条件,从而成功实现大块非晶合金的连铸制备。将大块非晶合金的连铸实验结果与模拟结果的对比,验证了连铸模型的准确性。
【Abstract】 There are many excellent performances of Bulk glassy alloys (BGA) because of their unique characteristic. The preparation of BGA is an important aspect in engineering application of BGA, therefore the investigation of high efficiency and low cast continuous manufacturing techniques of glassy alloys makes a good sense nowadays.In this paper, the current status about numerical simulation of amorphous alloys during casting solidification process is reviewed. The temperature fields of solidification of Zr-based BGA during cooper casting were also simulated. Through comparison of the calculation results and the experimental results, the accuracy of the mold, the influence of approximate treatment of thermal physical parameters of BGA and the thickness of copper were analyzed.On the base of existing research and the results of cooper casting, the numerical simulation of continuous casting of Zr48Cu36Ag8Al8BGA is studied. According to the characteristic of our continuous casting machine, the mathematical model of multi-mold is developed. The character of amorphous alloy melt during solidification and the influence of temperature with Zr-based amorphous had been analyzed. Through application of large-scale general-purpose finite element analysis software ANSYS, under the equations of heat transfer, initial conditions and boundary conditions, two-dimensional finite element model were established and the temperature field of the continuous casting process of Zr48Cu36Ag8Al8had been calculated. BGA had been calculated. The temperature field distribution contour and temperature-time curve of the main point during solidification were acquired.The simulation results of Zr48Cu36Ag8Al8BGA solidification process show that:in the multi-mold, the cooper mold with water made the main cooling effect and the graphite mold made little; among the casting parameters, pour temperature, cooling water flow rate and casting speed all made influence of the casting result. In order to meet the amorphous formation conditions, these parameters were discussed. At last, with the right parameters, the continuous casting experiments succeed, and the mold was proved correct.