Showing papers by "Y. A. Chang published in 2011"
TL;DR: The surface roughness of the epitaxial Fe4N films decreases with film thickness as mentioned in this paper, and there is in-plane biaxial magnetic anisotropy of the films.
Abstract: Epitaxial Fe4N thin films were grown on TiN buffered Si(001) substrate by dc reactive sputtering deposition at different substrate temperatures. Fe4N films epitaxially grew on TiN within the substrate temperature range from 250 to 350 °C. Lower than 250 °C there will be some other FexN compounds formed and higher than 400 °C there will be only Fe left. Fe4N is metastable and the postannealing process in vacuum will decompose Fe4N film to Fe. However, introducing 30% N2 in the postannealing atmosphere can stabilize the Fe4N up to 350 °C in the (Ar,N2) gas mixture. The surface roughness of the epitaxial Fe4N films decreases with film thickness. There is in-plane biaxial magnetic anisotropy of epitaxial Fe4N(001) on Si(001) with the [100] easy direction.
16 citations
TL;DR: PanPrecipitation as discussed by the authors is a software package that is integrated with the thermodynamic calculation engine, PanEngine, to obtain accurate thermodynamic properties and atomic mobility data necessary for precipitation simulation.
Abstract: Computer aided materials design is of increasing interest because the conventional approach solely relying on experimentation is no longer viable within the constraint of available resources. Modeling of microstructure and mechanical properties during precipitation plays a critical role in understanding the behavior of materials and thus accelerating the development of materials. Nevertheless, an integrated computational tool coupling reliable thermodynamic calculation, kinetic simulation, and property prediction of multi-component systems for industrial applications is rarely available. In this regard, we are developing a software package, PanPrecipitation, under the framework of integrated computational materials engineering to simulate precipitation kinetics. It is seamlessly integrated with the thermodynamic calculation engine, PanEngine, to obtain accurate thermodynamic properties and atomic mobility data necessary for precipitation simulation.
15 citations
TL;DR: Based on the calculated Fe-O stability diagram, single-phase Fe 3 O 4 films with tunable magnetic properties were fabricated on Si(0, 0, 1) substrates by selective oxidation with a CO 2 (g)/CO(g) mixture.
6 citations
TL;DR: In this article, the effect of adding 3 at.% Cr on the phase stability of the Ni-Al-Ir quaternary system was studied experimentally at 1250°C.
4 citations
TL;DR: In this article, the authors developed thermodynamic models for the phases in the Ti-Al-Cr system based on critically assessed binary models and ternary experimental data in literature, using the CALPHAD approach.
Abstract: Titanium aluminide based alloys are candidate materials for high temperature structural applications. They are typically alloyed with elements such as Nb, Ta, Mo, Cr and B for property enhancement. To understand the relationship between microstructure and alloy composition/processing condition, detailed models of phase equilibria in multicomponent Ti-Al based alloys are needed. In this work, we developed thermodynamic models for the phases in the Ti-Al-Cr system based on critically assessed binary models and ternary experimental data in literature, using the CALPHAD approach. Isothermal sections at 1200, 1150, 1000 and 800°C, and the liquidus projection, were calculated from the currently developed thermodynamic models; these are in satisfactory agreement with experimental data. Isopleths were calculated at specified Cr concentrations, and solidification paths were simulated under the Scheil conditions for a range of Ti-Al-Cr alloys. From the calculated phase diagrams and solidification paths, the effect of Cr on the microstructure of Ti-Al alloys can be understood.