Late News Poster Session: Characterization
Program Organizers: TMS Administration
Tuesday 5:30 PM
March 21, 2023
Room: Exhibit Hall G
Location: SDCC
L-60: An Evaluation of Advanced EBSD Methods for Phase Detection in Martensitic Steels: Patrick Callahan1; David Rowenhorst1; Richard Fonda1; 1US Naval Research Laboratory
Electron backscattered diffraction (EBSD) mapping has become a powerful tool for the evaluation of alloy microstructures due to its ability to clearly differentiate between phases and crystallographic orientations, thereby providing clear descriptors of grain size and morphologies. However, due to the high amount of plastic strain present in some alloys, such as martensitic steels, the EBSD signal can be weak and difficult get reliable indexing. Because even small amounts of retained austenite can strongly influence the properties of a steel, this study evaluates the ability of two different pattern processing and indexing methods, Dictionary Indexing and Non-Local means Pattern Reindexing (NLPAR), to improve the indexing success in a martensitic steel with a minority of retained austenite. We will show that both methods improve the indexing success rate by an order of magnitude, and can accurately differentiate between the BCC-indexed martensite and the FCC austenite.
L-61: Analysis of Alkali Element Distributions Using Atom Probe Tomography: Daniel Schreiber1; Kayla Yano1; 1Pacific Northwest National Laboratory
Alkali species (e.g. Li, Na, and K) play important roles in many technological applications, ranging from glass science to batteries and nuclear reactors. Their importance in these applications originates in part from their unique group chemistry, which also results in unique challenges for their characterization by some analytical techniques. As an example, atom probe tomography is a powerful 3D analytical technique that relies on field evaporation at cryogenic temperatures to controllably remove and reconstruct atomic positions and identities. For alkali species, this process is complicated by their relatively low evaporation field and high surface diffusivities. In this poster, I will outline out strategies for approaching the characterization of alkali species via atom probe tomography, the current limitations of these methods and corresponding analyses, and potential paths forward for further improving the method and understanding of alkali distributions in a variety of materials systems.
L-62: Characterization of Precipitate Size Distribution in Friction-stir Processed Al-7085 Using Small-angle X-ray Scattering and Correlative Microscopy Techniques: Rakesh Kamath1; Jonova Thomas1; Hrishikesh Das2; Tanvi Ajantiwalay2; Julian Escobar2; Jia Liu2; Jan Ilavsky1; Piyush Upadhyay2; Mert Efe2; Arun Devaraj2; Dileep Singh1; 1Argonne National Laboratory; 2Pacific Northwest National Laboratory
Friction stir processing (FSP) is a versatile method which allows for localized property modification as demanded by the end application. In the present study, Al7085 alloy sheets were subjected to FSP as a function of various process parameters (rotation speed and toolhead velocity), a certain combination of which resulted in higher bendability. It is well known that bendability/formability in Al-alloys is significantly affected by the nature of the precipitates/dispersoids present. Results from correlative microscopy tools (atom probe tomography (APT) and transmission electron microscopy (TEM)) revealed that the volume fraction of Al3Zr dispersoids and MgZn2 precipitates varied considerably in different process-affected zones. To characterize these precipitates/dispersoids in a statistically significant volume, combined ultra-small-angle (USAXS), small-angle (SAXS) and wide-angle (WAXS) x-ray scattering measurements were performed at beamline 9-ID-C, APS. The size and number density obtained from the SAXS analyses were in-line with the microscopy results and the trends seen in bendability.
L-66: Characterizing Mechanical Properties Using Physics-Informed Neural Networks and Multi-Fidelity Deep Learning: Ming Dao1; 1Massachusetts Institute of Technology
Instrumented indentation is widely used for evaluating elastoplastic material properties, especially when testing standard coupon samples is challenging. Despite significant progress made in recent years, a robust and accurate method is still missing for extracting the full stress-strain behavior from indentation test data. Multi-fidelity deep-learning algorithms are trained to obtain elastoplastic properties of metals and alloys from instrumented indentation, using simulation and experimental datasets with different levels of fidelity/accuracy. The accuracy and advantages of the unique approach have been validated for different commercial alloys, including six additively manufactured titanium alloys. Characterizing internal structures and defects in materials is another challenging task. A general method based on physics-informed neural networks (PINNs) is developed for obtaining unknown geometric and material parameters, with solid mechanics equations built in and boundary conditions parameterized within a meshless framework. The method is validated for materials with internal voids/inclusions using constitutive models including linear elasticity, hyperelasticity, and plasticity.
L-63: Crack Propagation Behavior of Fex(CoCrMnNi)100-x Multi-component Alloys: Hyunwoo Seo1; Hoodahm Lee1; Yubeen Hong1; Junggeun Park1; Hyokyung Sung1; 1Kookmin University
We have analyzed the crack growth behavior in a plane stress condition of the Fex(CoCrMnNi)100-x high entropy alloy at room and cryogenic temperatures. Twinning is dominant at room temperature while ε-martensite is formed together with twins at cryogenic temperature. Parallelly located twin boundaries and ε-martensite are not effective to resist the crack growth due to crack propagation along twin boundaries, while tiny α′-martensite can hinder the crack propagation leading to increase in resistance to crack growth. At cryogenic temperature, crack blunting is occurred by a large amount of pre-transformed α′-martensite prohibiting the further crack propagation. The compressive stress in front of crack tip by the formation of α′-martensite is also helpful to enhance the crack blunting. This result is contrary to the trend in which α′-martensite is harmful to crack growth resistance.
Differential Scanning Calorimetry as a Fingerprinting Technique to Detect Historical Uranium Enrichment in PCTFE: Nouf Almousa1; Rachel Connick2; Kevin Woller2; R. Scott Kemp2; Michael Short2; 1Princess Nourah University; 2MIT
The concept has been proven: the ability to detect irreversible calorimetric fingerprint of low radioactivity from uranium alpha emissions in the common enrichment gasket material PTFE [1]. Similar to the PTFE, the polychlorotrifluoroethylene (PCTFE) is one of the materials that can be found in uranium enrichment equipment. In this work, a thermal analysis technique, the differential scanning calorimetry (DSC), is used to observe the melting and recrystallization of the semi-crystalline polymer PCTFE. The DSC-measured bulk thermal properties are found to be statically sufficiently sensitive to the effect of very low alpha radiation doses. Additionally, the shifting and the changing in the shape of the melting and recrystallization peaks may lock in valuable information on the peak area and the thermal properties of the material which can be correlated with the alpha particle fluence, and hence, pave the way for fingerprinting of uranium enrichment for nuclear forensics.
L-64: In Situ Observation Study of MgO–C Dissolution Behavior in CaO–SiO2–Al2O3 Slag at High Temperature: Yongsug Chung1; Seungwook Lee1; 1Tech University of Korea
In situ dissolution behavior of MgO–C (0~18 wt%) in CaO–SiO2–Al2O3 slag was observed using a Single Hot Thermocouple Technique (SHTT) at 1550 C. When the slag was completely melted, MgO–C particles were added, and the dissolution behavior was observed in real time. Comparing the dissolution behavior of MgO and MgO–C revealed that the dissolution time of MgO was shorter than that of MgO–C with bubble formation. When the C content of MgO–C was 10 wt% or more, particle fragmentation was observed, and the dissolution time decreased. The main reaction of bubble formation was C(s) + SiO2(l) = CO(g) + SiO(g) based on thermodynamic analysis and weight loss measurements where the total partial pressure was PT = PCO + PSiO = 0.18 atm. The dissolution behavior of MgO–C in slag strongly depended on the effective C surface area.
L-65: Microstructural Characterization of Malachite Green Particles in Treated Wood: Mohamad Zbib1; Temitope Aminu2; David Bahr1; 1Purdue University; 2Intel Corporation
A variety of different processes exist which are capable of incorporating malachite (a copper carbonate) green particles in wood to serve as preservatives; but they use a variety of pressure and temperature regimes which may alter the structure and location of the copper-containing compounds in wood. Electron microscopy identified particulate features and chemical species in the wood samples consistent with malachite. However, X-ray diffraction suggests an absence of a crystalline malachite structure upon infiltration in the wood during processing. This suggests that, based on the fabrication process, wood structure may alter formation pathways of malachite in such a manner as to modulate its crystal structure or long-range order.
Nano-scale Structural Evolution and Mechanical Characteristics of Equiatomic AlCoCrNi High-entropy Alloy: Elyorjon Jumaev1; Orifjon Mikhliev2; Khasanjon Shanazarov2; Amir Abidov1; 1Almalyk Mining and Metallurgical Combine JSC; 2FDI «UZLITI ENGINEERING» LLC
In this work, crystal structure and mechanical behaviors of quaternary AlCoCrNi-based high-entropy alloy were investigated. The alloy was prepared by vacuum arc casting and studied and annealed at 873 K for 24, 72, and 192 h. The XRD patterns indicated the formation of body-centered cubic (BCC) crystal structure in the as-cast sample, however, hcp patterns were observed in heat-treated samples. The microstructure of the alloys showed dendrite and matrix areas. The fine microstructure of the dendrite and matrix area of the as-cast sample was found to be spherical participates and basket weave morphology, respectively. After annealing at different maintenance times, grain growth was observed in the morphology of the matrix area and phase transformation happened in the dendrite area. The alloy exhibits excellent compressive properties. However, after annealing mechanical properties of the alloy resulted in continuous strengthening in yield strength and loss of elasticity.