Thermodynamic analysis and modeling of novel ternary Ni-S-based bulk metallic-forming systems

我们提出应用相图计算（CALPHAD）方法来模拟多组分金属玻璃形成系统的热力学。本课题重点研究了新型三元大块金属玻璃（BMG）成形体系Ni-X-S，其中X=Pd, Ti, Nb。与常见的五元bmg形成体系相比，三元体系相对简单，有利于CALPHAD建模的应用。虽然我们的实验研究将包括所有三种Ni-X-S系统的二元和三元组成，但重点将首先放在Ni-Pd-S系统的建模上，因为就平衡热力学而言，它是一个简单的系统，并且平衡相的大量实验数据已经在文献中可用。现有的calphad型模型将得到扩展和发展，不仅用于描述热力学稳定相图（二元和三元），而且还用于描述过冷液体的亚稳态。我们自己的实验数据将被评估和处理，因此它们可以作为CALPHAD建模和计算的关键输入数据。实验工作包括量热（DSC/DTA, Flash-DSC， MDSC）和结构和微观结构检查（XRD, SEM/TEM）。物理性质测量系统（PPMS）也将用于温度低至50 K。作为这个项目的结果，这将是第一次，对于三元系统的过冷液体的热力学下降到玻璃化转变，相对于竞争的晶体相，将被现实地建模，因为我们将与大量真实的实验输入数据相配合。

We propose to apply the CALPHAD (CALculation of PHAse Diagrams) approach to model the thermodynamics in multicomponent metallic glass-forming systems. The novel ternary bulk metallic glass (BMG)-forming systems Ni-X-S, with X=Pd, Ti, Nb are the focus of this project. The relative simplicity of the ternary systems in comparison to the commonly found quinary BMG-formers facilitates the application of the CALPHAD modeling. While our experimental investigations will include binary and ternary compositions for all of the three Ni-X-S systems, emphasis will be given first to the modeling of the Ni-Pd-S system, because it is a simple system in terms of equilibrium thermodynamics and extensive experimental data of the equilibrium phases are already available in the literature. Existing CALPHAD-type models will be extended and new will be developed not only for the description of the thermodynamic stable phase diagrams (binaries and ternary), but also for the thermodynamic description of metastable states of the undercooled liquid. Our own experimental data will be assessed and processed, so they can serve as the crucial input data for CALPHAD modeling and calculations. The experimental work includes calorimetry (DSC/DTA, Flash-DSC, MDSC) and structural and microstructural examinations (XRD, SEM/TEM). A physical property measurement system (PPMS) will also be used for temperatures down to 50 K. As a result of this project, this will be the first time that for ternary systems the thermodynamics of the undercooled liquid down to the glass transition in relation to the competing crystalline phases will be realistically modeled, since we will underpin our fits with a large number of real experimental input data.