Intermetallic Phases Identification and Diffusion Simulation in Twin-Roll Cast Al-Fe Clad Sheet

Aluminium steel clad materials have high potential for industrial applications. Their mechanical properties are governed by an intermetallic layer, which forms upon heat treatment at the Al-Fe interface. Transmission electron microscopy was employed to identify the phases present at the interface by selective area electron diffraction and energy dispersive spectroscopy. Three phases were identified: orthorhombic Al5Fe2, monoclinic Al13Fe4 and cubic Al19Fe4MnSi2. An effective interdiffusion coefficient dependent on concentration was determined according to the Boltzmann–Matano method. The highest value of the interdiffusion coefficient was reached at the composition of the intermetallic phases. Afterwards, the process of diffusion considering the evaluated interdiffusion coefficient was simulated using the finite element method. Results of the simulations revealed that growth of the intermetallic phases proceeds preferentially in the direction of aluminium.

Industry Cluster Innovation Upgrading and Knowledge Evolution: A Simulation Analysis Based on Small-World Networks

This article focuses on the innovation and knowledge evolution of industry clusters. We examine the effects of the hub firm and the interaction of network member firms on the upgrading of the cluster. Our study is based on two patterns of knowledge learning and innovation, namely, STI (science, technology, and innovation) and DUI (doing, using, and interacting). This article adopts a knowledge diffusion simulation model to study the exchange of knowledge between cluster network actors in the context of small-world networks. The results indicate that we must pay close attention to the influence of hub enterprises on cluster evolution. Although hub companies may have certain innovation capabilities, if knowledge absorption problems among members are not properly resolved in the cluster network, the innovation performance of the local clusters is likely to be weakened, despite the success of the hub firm.

Mathematical Simulation of the Wettability of Al2O3 Substrate through Different Aluminum Alloys

The wetting process of a ceramic substrate (Al2O3) with and without carbon coating by means of aluminum-based alloys has been investigated. A mathematical simulation that predicts wettability in the systems under study is proposed, taking into account the diffusional effects of the used constituents. The prediction of the mathematical simulation is compared with the experimental results obtained for the same systems in question. From the results obtained, it was found that the wettability of a liquid droplet of aluminum and aluminum alloys on an alumina (Al2O3) substrate with and without carbon coating can be well represented by the proposed mathematical diffusion simulation. On the other hand, the control mechanism of the contact angle in relation to the deposition of a thin layer of carbon on the ceramic substrate (Al2O3) and the presence of metals such as La and Y in the aluminum alloy, give way to the formation of Al4C3, La2O3 and Y2O3 and these types of reaction help in the decrease of the contact angle.

Diffusion Simulation in SUS 430 Stainless Steel Interconnect with a MnCu Coating at 800°C

(MnCu)3O4 spinel coatings are good candidates for Cr-positioning protection on stainless steel interconnect. The spinel coatings can be formed by sputtering MnCu followed by a hot oxidation treatment. To understand how the elements diffuse in the MnCu-steel system, a homogenization diffusion-couple model was built with consideration for Mn oxidation at the coating surface. According to the simulation, the diffusion of Fe from the steel substrate to the MnCu coating occurred while Cr was almost trapped under the MnCu coating. Cu-rich metallic phase formed under the Mn-oxide layer early in the process. The solid solubility of Cr in such Cu phase was very low which can function as a Cr blocker so that Cr external oxidation can be inhibited. The inward diffusion of Mn from the coating to the substrate was caused by the formation of a Mn concentration peak at the interface which, based on thermodynamic simulations, was probably due to the dissolution of Mn with Fe and Cr.