Oxidation resistance of graphene-coated Cu and Cu/Ni alloy

The ability to protect refined metals from reactive environments is vital to many industrial and academic applications. Current solutions, however, typically introduce several negative effects, including increased thickness and changes in the metal physical properties. In this paper, we demonstrate for the first time the ability of graphene films grown by chemical vapor deposition to protect the surface of the metallic growth substrates of Cu and Cu/Ni alloy from air oxidation. SEM, Raman spectroscopy, and XPS studies show that the metal surface is well protected from oxidation even after heating at 200 \degree C in air for up to 4 hours. Our work further shows that graphene provides effective resistance against hydrogen peroxide. This protection method offers significant advantages and can be used on any metal that catalyzes graphene growth

Grain refinement of high alloy stainless steels in sand and directionally solidified castings

The goal of this research project is to develop an industrially viable melting process that will control the crystallization macrostructure of austenitic grades of cast steels. Titanium nitride (TiN) has proven to be an effective grain refiner of austenite. Theoretical simulation and experimental application has led to the development of a repeatable grain refining melt process for austenitic stainless steel alloys. Grain refinement of the as-cast structure of Cr-Ni stainless steel alloys solidified with primary FCC, BCC and dual FCC/BCC phases was studied experimentally. Refinement was achieved in both cast ferritic and austenitic grades. Dual solidification of FCC/BCC phases resulted in an unrefined macrostructure. It is proposed that solidification sequence can limit the grain refining capability of heterogeneous nuclei. Two inoculation-based melt practices were developed to study grain refinement in cast austenitic stainless steels. The first includes in-situ formation of TiN on to Mg-Al spinel oxides, and the second involves master alloy additions containing preformed TiN. The master alloy method extended the equiaxed zone and improved the distribution of TiN in the casting. The in-situ method showed more effective grain size refinement. The effect of the developed grain refining melt practice on the properties of cast superaustenitic stainless steel (similar to CK3MCuN) was examined. Heat treatment had no effect on the as-cast grain size. The grain refined alloy exhibited a reduction in segregation after heat treatment; an increase in ultimate tensile strength (+11%), yield strength (+13%), ductility (+8%), hardness (+2%), pitting corrosion; a decrease in impact strength and intergranular corrosion rate in comparison to the unmodified, base alloy --Abstract, page iv

An integrated formal methods tool-chain and its application to verifying a file system model

Tool interoperability as a mean to achieve integration is among the main goals of the international Grand Challenge initiative. In the context of the Verifiable file system mini-challenge put forward by Rajeev Joshi and Gerard Holzmann, this paper focuses on the integration of different formal methods and tools in modelling and verifying an abstract file system inspired by the Intel (R) Flash File System Core. We combine high-level manual specification and proofs with current state of the art mechanical verification tools into a tool-chain which involves Alloy, VDM++ and HOL. The use of (pointfree) relation modelling provides the glue which binds these tools together.Mondrian Project funded by the Portuguese NSF under contract PTDC/EIA-CCO/108302/200

Towards scaling up DynAlloy analysis using predicate abstraction

DynAlloy is an extension to the Alloy specifi cation language suitable for modeling properties of executions of software systems. DynAlloy provides fully automated support for verifying properties of programs, in the style of the Alloy Analyzer, i.e., by exhaustively searching for counterexamples of properties in bounded scenarios (bounded domains and iterations of programs). But, as for other automated analysis techniques, the so called state explotion problem makes the analysis feasible only for small bounds. In this paper, we take advantage of an abstraction technique known as predicate abstraction, for scaling up the analysis of DynAlloy specifi cations. The implementation of predicate abstraction we present enables us to substantially increase the domain and iteration bounds in some case studies, and its use is fully automated. Our implementation is relatively e cient, exploiting the reuse of already calculated abstractions when these are available, and an "on the fly" check of traces when looking for counterexamples. We introduce the implementation of the technique, and some preliminary experimental results with case studies, to illustrate the benefi ts of the technique.VI Workshop Ingeniería de Software (WIS)Red de Universidades con Carreras en Informática (RedUNCI