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首页> 外文会议>IAC;International Astronautical Congress >Multiphase Transformations of Glass-Forming Alloys Investigated on Earth and in Reduced Gravity (MULTIPHASE)
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Multiphase Transformations of Glass-Forming Alloys Investigated on Earth and in Reduced Gravity (MULTIPHASE)

机译：在地球上和降低重力下研究玻璃形成合金的多相转变（MULTIPHASE）

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Within MULTIPHASE project, it is envisaged to investigate multi-phase transformations in non-equilibrium systemsto test models of phase transformations against experiment. Electromagnetic levitation (EML) of droplets allowsto undercooling liquid metallic alloys far below their respective melting temperatures. Various non-equilibriumeffects can be investigated during rapid solidification. Phenomena studied include: solute trapping of solid solutionsand disorder trapping of intermetallics during rapid dendrite growth, a transition from regular to anomalous growthin eutectic alloys, and at extreme undercoolings glass formation. In particular, multicomponent alloys form metastablemultiphase solids upon undercooling prior to solidification. In many cases de-mixing processes in the liquidstate prior to solidification control multiphase crystallization of multicomponent alloys. On this reason, de-mixingprocesses in monotectic systems and spinodal decomposition are in the focus of the present work, investigated bothfrom theoretical and experimental side. Theoretically, we apply sharp interface model of solidification to prescribeand explain effects of disorder and solute trapping as well as we use methods of diffuse interfaces to model phaseseparation by spinodal mechanism and glass transition. Specifically, for methods of diffuse interfaces, we use thephase field method, which is a useful tool for predicting evolution of metastable microstructures.The experimental research is divided into three parts. The Co-Cu system is used to study de-mixing in binary liquids.The Co-Cu system shows a metastable miscibility gap in the regime of the undercooled liquid. By applyingelectromagnetic levitation the Co-Cu liquid can be undercooled into the miscibility gap and is rapidly solidified dueto the great driving force for rapid crystallization. The Cu-Zr system is chosen to measure the dendrite growth velocityas a function of undercooling. The intermetallic Cu_(50)Zr_(50) alloy is a glass forming system with high reduced glasstransition temperature. The Cu_(46)Zr_(54) alloy forms a eutectic microstructure. Both, the intermetallic and the eutecticalloy show sluggish growth behaviour so that effects of forced convection on heat and mass transport are expected.Two multicomponent bulk-glass-forming systems are investigated with respect to their glass forming ability withand without convection. These are a Zr-based alloy as Zr_(58.5)Cu_(15.6)Ni_(12.8)Al_(10.3)Nb_(2.8) and a metal-metalloid alloy asPd_(40)Cu_(30)P_(20)Ni_(10). The former alloy is qualified for experiments using the Electro-Magnetic Levitator (EML) developedby DLR/ESA and the latter one is qualified for experiments using the Multi-Zone-Electro-Vacuum (MZEV)furnace developed by ROSKOSMOS. The experiments on board the International Space Station are scheduled for2012/2013.
机译：在MULTIPHASE项目中，设想研究非平衡系统中的多相转换 对照实验测试相变模型。液滴的电磁悬浮（EML）允许 将液态金属合金过冷至远低于其各自的熔化温度。各种非平衡 可以在快速凝固过程中研究其效果。研究的现象包括：固溶体的溶质捕集 枝晶快速生长过程中金属间化合物的无序俘获，从规则生长到异常生长 在低共熔合金中，以及在极度过冷的情况下，会形成玻璃。特别是多组分合金形成亚稳态 凝固前在过冷时产生多相固体。在许多情况下，液体中的去混合过程 凝固前控制多组分合金的多相结晶。出于这个原因，去混合 单晶体系中的过程和旋节线分解是本研究的重点，对这两种方法都进行了研究。 从理论和实验的角度来看。从理论上讲，我们采用凝固的锐化界面模型来规定 并解释无序和溶质捕获的影响，以及我们使用扩散界面的方法对相进行建模 通过旋节线机理和玻璃化转变分离。具体来说，对于分散接口的方法，我们使用 相场法，这是预测亚稳态微观结构演变的有用工具。 实验研究分为三个部分。 Co-Cu系统用于研究二元液体中的去混合。 Co-Cu系统在过冷液体状态下显示出亚稳态的混溶性间隙。通过应用 电磁悬浮Co-Cu液体可被过冷至混溶间隙并由于以下原因而迅速固化 快速结晶的强大动力。选择Cu-Zr系统来测量枝晶生长速度 作为过冷的函数。金属间Cu_（50）Zr_（50）合金是高还原玻璃的玻璃成型系统 转变温度。 Cu_（46）Zr_（54）合金形成共晶微观结构。金属间和共晶 合金显示出缓慢的生长行为，因此可以预期强制对流对热量和质量传递的影响。 研究了两种多组分块状玻璃成型系统的玻璃成型能力 而且没有对流。它们是Zr_（58.5）Cu_（15.6）Ni_（12.8）Al_（10.3）Nb_（2.8）的Zr基合金和 Pd_（40）Cu_（30）P_（20）Ni_（10）。前一种合金可以使用开发的电磁悬浮器（EML）进行实验 由DLR / ESA获得，而后者则有资格使用多区域电真空（MZEV）进行实验 ROSKOSMOS开发的熔炉。预定在国际空间站上进行的实验 2012/2013。

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