Phase Transformations and Microstructural Evolution: Poster Session
Sponsored by: TMS Materials Processing and Manufacturing Division, TMS: Phase Transformations Committee
Program Organizers: Yufeng Zheng, University of North Texas; Rongpei Shi, Harbin Institute of Technology; Stoichko Antonov, University of Science and Technology Beijing; Yipeng Gao, Jilin University; Rajarshi Banerjee, University of North Texas; Yongmei Jin, Michigan Technological University
Tuesday 5:30 PM
February 25, 2020
Room: Sails Pavilion
Location: San Diego Convention Ctr
O-33 (Invited): HyMARC Multiscale Modeling Approaches for Investigating Thermodynamic and Kinetic Phase Behaviors of Metal Hydrides: Tae Wook Heo1; ShinYoung Kang1; Xiaowang Zhou2; Rongpei Shi1; Brandon Wood1; 1Lawrence Livermore National Laboratory; 2Sandia National Laboratories
Solid-state hydrogen storage materials utilize metal-hydrogen interactions to store hydrogen by forming metal hydrides. The operating mechanisms involve concurrent surface reaction, hydrogen diffusion, and phase transformation. Essentially, these are collective dynamic processes of atomic/molecular species that determine the thermodynamics and kinetics of nano- or micro-level characteristics. Therefore, several modeling approaches that cover different length and time scales ought to be properly integrated for comprehensively exploring multiscale science of hydrogen storage mechanisms. In this presentation, we will introduce our integrated effort as part of the DOE Hydrogen Storage Materials—Advanced Research Consortium (HyMARC) towards the multiscale modeling for metal hydrides. We will discuss our development of an integrated framework that combines materials information from atomistic simulations and materials phenomena described by mesoscale models. In particular, representative case studies will be presented, including beyond-ideal thermodynamic modeling, effective mass transport/mechanical response modeling, and phase-field modeling of phase transformations of metal hydrides during (re/de)hydrogenation.
Cancelled
O-34: Abnormal Temperature Dependence of Critical Transition Stress in Nanocrystalline NiTi Shape Memory Alloys: Taotao Wang1; Kaiyuan Yu1; Lishan Cui1; 1China University of Petroleum, Beijing
Nanocrystalline near-equiatomic NiTi shape memory alloys with an average grain size of ~ 20 nm were fabricated by wire drawing and annealing. Tensile tests at various temperatures show that the temperature dependence of the critical transition stress can be divided into three regions, as manifested by ~ 4.7 MPa/K at high temperatures, ~ 3.1MPa/K at intermediate temperatures and ~ 0 MPa/K at low temperatures. In situ high energy X-ray diffraction reveals that the phase structure of the alloys are sole B2, B2/R mixture and sole R in the three regions, respectively. It is suggested that the abnormal temperature dependence and the phase structure of the alloys are related to the restricted martensitic transformation at nanoscale.
O-35: Bainite Formation during Zinc Galvanizing on Steel: Bong-Kyu Kim1; Jun Hyun Han1; 1Chungnam National University
Hot-dip galvanizing is known as a surface treatment to prevent steel corrosion by forming Zinc plating layers on the steel surface. However, because Zinc is melted, there are problems with thickness, low plating adhesion, and poor uniformity. Small amount of Al is added to improve plating adhesion and uniformity. Mg is added to improve corrosion resistance. The addition of Mg facilitates the formation of the corrosion-producing Simonkolleite on plated layer of Zn-Mg-Al and has high corrosion resistance of 5-10 times than existing Hot-dip galvanizing. The temperature of the Zn-Mg-Al alloy plating bath is between 440°C and 460°C, which is known to be similar to that of Bainite formation during heat treatment of steels. Therefore, in this study, zinc plating was performed at the formation temperature of Bainite to achieve both the improvement of corrosion resistance by galvanizing and the enhancement of strength and ductility due to the formation of Bainite.
O-36: Carbon and Microstructure Effects on the Magnetic Properties of Fe-CN Soft Magnetic Materials (Minnealloy): Guannan Guo1; Jinming Liu1; Jian-Ping Wang1; 1University of Minnesota
In this report, we investigate the effects of carbon and microstructure of the precursor on the magnetic performance based on a developed method for bulk preparation to synthesis Fe-CN magnetic materials. The melt-spun ribbons of Fe-C can be obtained to improve the efficiency of the nitrogen diffusivity by introducing porous and defects inside the grains, which increases the volume fraction of α”-Fe16N2. The carbon effects were studied by the X-ray diffraction (XRD) and Wavelength-dispersive spectroscopy (WDS) to reveal the redistribution of carbon during the treatment and the effects on nitriding. The Fe-C precursor prepared by melt spinning and the microstructure variation during the treatment is obtained by the Scanning Electron Microscopy (SEM) and Transmission electron microscopy (TEM) to reveal the formation of porous during the oxidation/reduction and the movements of the carbon atoms.
O-37: Carbonation Behavior of Calcium Aluminate Cements with Additions of Silica: John Zapata1; Henry Colorado1; 1Universidad de Antioquia
In this research, different formulations of calcium aluminate cements (CAC) pastes with 51 and 71wt% Al2O3 were made at 0.4 water to cement ratio (W/C) with additions of 0, 10 and 20wt% silica. Both the raw cement powders and their corresponding samples after hydration were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), density and compression tests. Samples were exposed to 20°C in a furnace open to air, for 3, 4 and 7 days with a concentration of CO2 of 4% and relative humidity of 70%. The behavior of the constituent phases with the temperature was also studied through of thermal gravimetric analysis (TGA) and the corresponding derivative thermogravimetry (DTG).
O-38: Dealloyed High-strength Metallic Coatings: Bernard Gaskey1; Ian McCue2; Michael Brupbacher2; Jonah Erlebacher3; 1Nanyang Technological University; 2Johns Hopkins University Applied Physics Laboratory; 3Johns Hopkins University
Liquid metal dealloying (LMD) is an emerging process where partial dissolution of an alloy in a metallic melt drives the evolution of a topologically complex structure. Usually, this is accomplished by immersing the solid alloy in a liquid metal, but an alternative technique is to heat a part to induce partial melting. Here, we demonstrate the latter method by applying a coating to a nickel alloy surface via plasma spray, selected so that the interface between the coating and substrate undergoes eutectic melting when heated. The subsequent dealloying reaction densifies the coating while forming a sub-micron scale composite structure with exceptional mechanical properties. This work demonstrates the scalable fabrication of an extremely strong coating for nickel alloy systems and provides a framework for the development of coatings for other structural metals.
O-39: Dilatometric Analysis of the Martensite Decomposition by Stages during Continuous Heating: Perla Díaz-Villaseñor1; Octavio Vázquez-Gómez1; Eliuth Barrera-Villatoro1; Héctor Vergara-Hernández1; Edgar López-Martínez2; Bernardo Campillo-Illanes3; 1Tecnológico Nacional de México / I.T. Morelia; 2Universidad del Istmo; 3Universidad Nacional Autónoma de México
The martensite decomposition by stages was studied in an experimental medium-carbon steel alloyed with vanadium under conditions of continuous heating and differential dilatometry. For the dilatometric analysis, cylindrical specimens of 5 mm diameter and 15 mm length were machined and heated at different rates: 0.58, 0.75 and 0.91 °C s-1 until reaching a temperature of 1000 °C, then the specimens were cooled to room temperature. Through the dilatometric analysis and the strain rate by dilation, the critical points corresponding to the martensite decomposition stages were determined, and the energies of activation by stages were calculated employing the Kissinger method. Lastly, five critical points associated with stages of dissolution, precipitation and phase transformation were identified, as well as observing that the critical points displacement to higher temperatures as the heating rate increases, while the values of the activation energies were agreed to values reported for different stages of martensite decomposition.
O-40: Enhanced Chalcopyrite Bioleaching by Combined Catalysis of Activated Carbon and Visible Light: Mo Lin1; Shitong Liu1; Hao Lin1; Baojun Yang1; Jun Wang1; Guanzhou Qiu1; 1Central South University
The effects of activated carbon and visible light on chalcopyrite bioleaching by Acidithiobacillus ferrooxidans (A. ferrooxidans) were investigated in this study. The results indicated that the dissolved copper in the visible light group without activated carbon and the dark group with activated carbon was higher than that of the control without visible light and activated carbon, respectively.In this study,bioleaching experiments,synchrotron X-ray Diffraction(SR-XRD),X-ray absorption near edge structure (XANES) and X-ray Photoelectron Spectroscopy (XPS) were conducted to investigate the specific mechanism about catalysis of activated carbon and visible light.Results revealed that catalytic effect was mainly attributed to the promotion of ferric iron/ferrous iron cycling and the inhibition of passivation layer formation on chalcopyrite surface.
Cancelled
O-41: Enhanced Toughness of Nanograined Metallic Thin Films on Flexible NiTi Shape Memory Alloy Substrates: Gan Zhang1; Kaiyuan Yu1; Taotao Wang1; 1China University of Petroleum-Beijing
Metallic thin films on metal substrates exhibit limited toughness and typically rupture at strain of a few percent due to stress concentrations at the film/substrate interfaces during deformation. In this work, we deposited nanograined Cu films on top of flexible NiTi shape memory alloy substrates. It is anticipated that the uniform lattice shear and strain hardening of the NiTi substrates can relieve the stress concentrations at the film/substrate interfaces effectively, leading to enhanced toughness of the thin films. We show that the nanograined Cu films on NiTi substrates retain uniform deformation without rupture up to ~ 24% applied strain, in contrast to ~ 6% for Cu films on steel substrates and ~15% for Cu films on Kapton substrates.
O-42: Hierarchical Microstructure Enhanced Comprehensive Mechanical Properties in Ti-Alloys: Mengyuan Hao1; Dong Wang1; Qiaoyan Sun1; Pei Li1; Tianlong Zhang1; Yunzhi Wang1; 1Xi'an Jiaotong University
The design of titanium alloys with strength-ductility synergy is challenge to materials science. We propose an effective way to improve the comprehensive mechanical properties of titanium alloys based on the design of special structure of β+α phases by integrating phase field simulations and experiments. Phase field simulations have been used to screen the microstructure and guide the following experimental heat treatment process. Based on this design strategy, a Ti-1023 alloys with special microstructure of α phase in β matrix is designed, which show an enhanced ductility by ~50% and strength by ~10% simultaneously. Our work not only shed light on the design of novel Ti-alloys with comprehensive strength and ductility properties, but also propose a promising way to improve the mechanical properties of all the precipitated strength traditional materials.
O-43: High-pressure Synthesis of HCP Nickel from a Metallic Glass: Abhinav Parakh1; Mehrdad Kiani1; David Doan1; X. Wendy Gu1; 1Stanford University
Nickel is a FCC metal at ambient conditions, as well as at elevated temperature and pressure. Here, we report the formation of HCP nickel from a nearly monoatomic metallic glass. Ni metallic glass nanoparticles that contain <5% boron are synthesized using colloidal methods. The thermodynamic stability of this material was tested by compressing the nanoparticles under hydrostatic pressure in a diamond anvil cell, and observing structural changes using x-ray diffraction. We found that the nanoparticles crystallized into an HCP lattice at ~10 GPa, which is lower than crystallization pressure of bulk metallic glasses. The nanoparticles remained HCP in structure after unloading. The post-compression transmission electron microscope imaging confirmed their HCP crystal structure, and the formation of nanocrystalline grains. We hypothesize the unique atomic structure of the nearly monoatomic Ni metallic glass and the differences in HCP and FCC elastic constants under pressure leads to the formation of this unusual material.
O-45: JMA Model Application to Elucidate the Kinetic Parameters in a Silicon Steel during Continuous Heating: Alexis Gallegos-Pérez1; Octavio Vázquez-Gómez1; José López-Soria1; Héctor Vergara-Hernández1; Pedro Garnica-González1; 1Tecnológico Nacional de México / I.T. Morelia
The kinetic parameters k and n of the Johnson-Mehl-Avrami model were determined according to the heating rate in an experimental medium-carbon steel alloyed with silicon. In this regard continuous heating dilatometric tests were carried out under an inert atmosphere and it was observed that the silicon content tends to displace austenite formation temperatures up to values higher than 1000 °C. Through the experimental data, the austenite volume fraction was calculated using the lever rule and fitted with the model. The fit showed an imprecision with respect to the extension of transformation by the presence of two peaks in the first derivative curve, suggesting changes in the transformation mechanisms due to the silicon content. Therefore, an analysis by stages was required to elucidate the kinetic parameters in each region to improve the approximation of the Johnson-Mehl-Avrami model and correlate the parameters with the nucleation and growth modes.
O-46: Microstructural Evolution during Solidification of Ternary Eutectic Al-Cu-Mg: Dominic Ezemenaka1; Amber Genau1; Christian Patino1; 1University of Alabama, Birmingham
In-depth understanding of how to precisely manipulate the microstructures of multi-phase alloys during solidification so as to meet the rapidly changing demands of technological advancement is a daunting task. This research seeks to increase our fundamental understanding of the parameters which control multi-phase solidification by studying the behavior of three-phase eutectic systems, which exhibit far more variability and complexity than standard binary eutectics. Directional solidification via a Bridgman furnace was used to investigate the behavior of Al-Al2Cu-Al2CuMg ternary eutectic over a range of growth rates and temperature gradients. In order to fully characterize the different microstructural morphologies observed, both qualitative and quantitative approaches are deployed, particularly with the help of parameters such as phase fraction, eutectic spacing, number of nearest neighbors, and shape factor. Particular attention is paid to the evolution of the microstructural patterns and crystallographic orientation relationships, resulting from grain competition, as the solidification distance increases.
Cancelled
O-47: Quasi-linear Superelasticity with Ultralow Modulus Induced by Nanoscaled Martensitic Phase Transition: Shuangshuang Zhao1; Qianglong Liang1; Chuanxin Liang1; Dong Wang1; Yuanchao Ji1; Yu Wang1; Xiaobing Ren1; Yunzhi Wang1; 1Xi'an Jiaotong University
We report a quasi-linear superelastiticy (~2%) with ultralow tunable elastic modulus (~20-30GPa) in NiTi shape memory alloys through pre-deformation. Heat flow measurments and dynamic mechanical analysis show the absent of normal martensitic phase transition and the occurrence of a nanoscaled phase transition with continuous response to the external loading and temperature. TEM observations suggest that this nanoscaled phase transition is triggered by the high density defects induced by pre-deformation. Our work may suggest an effective way to design unique phase transition with unprecedented properties.
O-48: The Interaction of Point Defects with Stress Fields Generated by Persistent Slip Bands in f.c.c. Nickel: Leslie Mushongera1; Pankaj Kumar1; Michael Sangid2; 1University of Nevada, Reno; 2Purdue University
A glance at available literature on mechanisms determining the characteristics of persistent slip bands (PSB) reveals that the subject remains fascinating, with many unresolved issues and disparate observations. The volumetric swelling of PSBs is one area where stipulated bridging between theory and experiments is yet to establish. We use a phase-field model to study the volumetric swelling of PSBs in nominally defect-free pure f.c.c metals. The scale of observation envisioned is that of PSBs intersecting a single crystal. The PSBs are regarded as a result of spontaneous evolution of localized dissipative structures in the form of solitary static regions. Basic building blocks of the theory are: a model of cyclic plasticity tailored to PSBs, coupled to a model of vacancy diffusion which accounts for volume diffusion, pipe diffusion. Our numerical simulations show that the flux of vacancies contributes to volumetric swelling and local damage in the vicinity the PSB/matrix interface.