General Poster Session: Physical Metallurgy
Program Organizers: TMS Administration
Tuesday 5:30 PM
February 25, 2020
Room: Sails Pavilion
Location: San Diego Convention Ctr
O-52 (Digital): Explaining the Martensitic Transformation by Optimizing the Strain: Felix Therrien1; Vladan Stevanović1; 1Colorado School of Mines
We present a new mechanism for the diffusionless transformation of steel from the austenite phase (γ) to the martensite phase (α). Our new mechanism is obtained by minimizing the total Euclidean distance traveled by all the atoms to go from one phase to the other. The resulting path, which has minimal principal strains, consists of a rotated Bain deformation, broken into slip planes every sixth (112)α plane. By minimizing the distance, we seamlessly obtain an invariant plane which makes our result perfectly compatible with the widely accepted Phenomenological Theory of Martensitic Transformations model. From our result we find the Kurdjumov-Sach orientation relationship (OR) and the {225}γ habit plane which have been both extensively reported in literature. We also provide a new explanation for the occurrence of the Pitsch OR in thin films.
Cancelled
O-53: Interaction between Cu and Cr Coadsorption on MnS Inclusions in Low Alloy Steel and Study of the Interfaces between α-Fe and MnS: Wenting Lv1; Luchun Yan1; Xiaolu Pang1; Huisheng Yang1; Lijie Qiao1; Yanjing Su1; Kewei Gao1; 1University of Science and Technology Beijing
The first principles calculations based on density functional theory and TEM experiments were employed to investigate the coadsorption of Cu and Cr on MnS inclusions in low alloy steel and the interfaces between α-Fe and MnS. The enrichments of Cu and Cr on MnS inclusions were observed by TEM. The atomic structures, electronic and energetic properties of clean and Cu or Cr adsorbed MnS surface were calculated. Besides, the interfacial properties such as the work of adhesion (Wad), interface energy (γint) and electronic structures of the interfacial structures were also calculated. Results show that Cu and Cr promote the adsorption of each other on MnS (100) surface and Fe (110)/MnS (110) is the most stable interfacial structure among the nine candidate interfaces. The orientation relationship of α-Fe and MnS was identified as Fe (110)∥MnS (110) by TEM, which is in good accordance with the calculated results.
O-54: Optimization of Oxidation Resistance and Mechanical Properties of Refractory High-entropy Alloys-futuristic Strategy: Saad Sheikh1; Hideyuki Murakami1; 1National Institute for Materials Science, Japan
Refractory high-entropy alloys (RHEAs), particular type of high entropy alloys (HEAs), comprising of mainly refractory metals. RHEAs have emerged as potential structural materials for ultrahigh-temperature applications. These novel alloys require a combination of balanced oxidation resistance and mechanical properties. Previous studies lack the guidelines to develop materials which can form a protective and stable oxide layer such as alumina during high temperature exposure in combination with optimum mechanical properties. Here, we have introduced a strategy to form a stable and protective alumina layer upon high temperature exposure for ductile RHEAs. Ductility is first achieved by maintaining the number of total valence electrons low, tuned by adjusting the alloy composition. Later, oxidation protection is enhanced by two step aluminizing i.e., low activity aluminizing followed by the high activity one. Furthermore, through this approach, the ductile RHEAs resistance to oxidation improved tremendously, thus bringing in a new perspective towards their development.