Phase Transformations and Microstructural Evolution: Martensitic Transformation
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
Monday 2:30 PM
February 24, 2020
Room: 33B
Location: San Diego Convention Ctr
Session Chair: Yongmei Jin, Michigan Technological University; Deep Choudhuri, New Mexico Institute of Mining and Technology
2:30 PM
Macroscopic Energy Barrier and Rate-independent Hysteresis in Martensitic Transformations: Yongmei Jin1; Yu Wang1; Armen Khachaturyan2; 1Michigan Technological University; 2Rutgers University
A thermodynamic theory for the lower-bound hysteresis in martensitic transformations is presented. It shows that the elastic energy generated by the transformation-induced crystal lattice misfit produces a macroscopic barrier between the parent and product phases. Since this energy barrier is proportional to the macroscopic volume of the system and thus cannot be surmounted by thermally assisted nucleation of new phase, a rate-independent hysteresis of thermodynamic nature is produced, which sets the lower bound for the total transformation hysteresis. This lower-bound hysteresis is characterized by two critical temperatures of the martensitic and reverse transformations, where the necessary undercooling and overheating are intrinsic material properties determined by the lattice parameters of the phases. The theory is tested against experimental observations in representative Ni-Mn-Ga and Fe-Ni alloys, and their drastically different hysteresis behaviors are discussed. Phase field microelasticity simulation of hysteresis in a cubic-to-tetragonal martensitic transformation in polycrystal is also presented.
2:50 PM
Concurrent Modeling of Martensitic Transformation and Crack Growth in Shape Memory Ceramics: Ehsan Moshkelgosha1; Mahmood Mamivand1; 1Boise State University
The dynamic interaction of martensitic transformation (MT) and crack growth in Shape Memory Materials (SMMs) is a less studied subject which broadly limited our fundamental understanding of the mechanisms behind mechanical degradation in SMMs. In this work, we developed a novel multiphysics model which coupled the Ginzburg-Landau equations of MT to variational formulation of brittle crack growth based on Griffith theory. The model is parameterized for single and polycrystalline zirconia which experience tetragonal to monoclinic phase transformation. The model’s predictions of anomaly crack growth path are in good agreement with the experiments. The model also reveals the critical role of crystal lattice orientation on transformation toughening and crack growth path. For instance in a constrained grain the maximum (minimum) toughening happens when a-axis of tetragonal phase makes the angle of 55 (90) degrees with the crack surface. The effect of grain size on the fracture toughness will also be discussed.
3:10 PM
The Effects of Quenching Medium and Cooling Rates on the Phase Transformation of γ’-Fe4N to Achieve Iron Nitride Martensite: Bin Ma1; Guannan Guo1; Jian-Ping Wang1; 1University of Minnesota
The phase transformation of Fe-N alloy during the quenching process from the γ’-Fe4N was investigated under different quenching mediums and cooling rates. The cooling rates were varied by choosing different quenching mediums including water, oil, and the liquid nitrogen with one step or multiple steps quenching. A mixture of iron nitride martensite with BCT structure, γ-FeN phase and residual γ’-Fe4N was obtained after the quenching of γ’-Fe4N. The magnetization continuously increased when the ambient temperature cooled down to 10 K, that the start temperature (250K) and finish temperature (160K) of the martensite transformation can be read from the curve of saturated magnetization vs. temperature. This report proposed a new model to synthesis iron nitride martensite from γ’-Fe4N through the nitrogen atoms diffusion during the quenching with the formation of γ-FeN as the transit phase.
3:30 PM
A Martensitic Transformation Kinetics Law Sensitive to Stress State Implemented in Crystal Plasticity for Modeling of Strain and Stress Driven Austenite to Martensite Transformation: Marko Knezevic1; Zhangxi Feng1; Milovan Zecevic2; 1University of New Hampshire; 2Los Alamos National Laboratory
Austenite to martensite transformations can be stress- or strain-induced. In the former case, austenite transforms directly to alpha-martensite at pre-existing nucleation sites. In the later case, the transformation occurs during plastic deformation through a process of nucleation at intersections of slip bands forming an intermediate epsilon-martensite phase, which subsequently transforms to alpha-martensite and a process of growth. As crystallographic texture has a strong influence on the active transformation mechanisms, an elasto-plastic self-consistent (EPSC) crystal plasticity model is used as a crystallographic platform to implement a phase transformations kinetics model, which is a physically enhanced version of the Olson-Cohen kinetics model considering both epsilon and alpha martensite. The model is applied to a comprehensive set of experimental data for metastable austenitic steels recorded under a variety of stress states at different temperatures and strain rates, including an impact deformation. The implementation and insights from these predictions are discussed in this paper.
3:50 PM
The Effect of Interface Compatibility and Grain Constraint in ZrO2-based Shape-memory Ceramics: Edward Pang1; Christopher Schuh1; 1Massachusetts Institute of Technology
ZrO2-based shape-memory ceramics (SMCs) offer the potential for significant benefits over shape-memory alloys (SMAs), including higher transformation temperatures, work output, and possibly environmental resistance. Despite these potential benefits, these materials have not yet reached their full potential because in polycrystal form they are limited by catastrophic cracking during the martensitic transformation, thus restricting previous efforts to micron-scale single-/oligo-crystals. However, we have recently found that improving interface compatibility during the martensitic transformation by meeting the cofactor conditions can reduce and possibly eliminate transformation-induced cracking, thus making polycrystalline SMCs potentially viable. We present recent results on some of these preferred compositions and correlate our experimental measurements of crystallographic compatibility with observed cracking of bulk polycrystals during thermal cycling experiments. We then compare these results with those in powders to reveal the role of grain constraint on characteristics of the martensitic transformation in these materials.
4:10 PM Break
4:30 PM Invited
Young Leaders International Scholar – JIM: Co-based Heusler Alloys with Reentrant Martensitic Transformation Behavior: Fundamentals and Application Possibilities: Xiao Xu1; Takeshi Kanomata2; Ryosuke Kainuma1; 1Tohoku University; 2Tohoku Gakuin University
In this presentation, I would like to deliver a brief review on the unique reentrant martensitic transformation (RMT) behavior in Co-based Heusler alloys. In Co2Cr(Ga,Si) alloys, an RMT behavior was reported. By this phenomenon, novel physical phenomena, such as the cooling-induced shape memory effect and inverse temperature dependence of superelastic stress, were reported. For a deeper understanding on these phenomena, the experimental phase diagrams, including the composition versus temperature (), magnetic field versus temperature () and uniaxial stress versus temperature () phase diagrams, will be introduced. The occurrence of the RMT behavior was found to be the result of the competition between the entropy change of the martensitic transformation and magnetic entropy of parent phase. A brief explanation of the thermodynamic analysis on the RMT behavior will be provided. Furthermore, application possibilities by the use of RMT behavior will also be discussed in this talk.
5:00 PM
Effect of Precipitates on Martensitic Transformation in NiTiHf Shape Memory Alloys: Taiwu Yu1; Yipeng Gao2; Peter Anderson3; Michael Mills3; Yunzhi Wang3; 1 Ohio State University; 2Idaho National Laboratory ; 3Ohio State University
Nanoscale coherent H-phase precipitates have strong effects on the B2 (cubic) to B19’ (monoclinic) martensitic transformation (MT) behavior in NiTiHf high-temperature shape memory alloys (SMAs). Two typical patterns of martensite coexisting with the H-phase precipitates are predicted by phase field simulations, i.e., plate-shaped precipitates of 70-250 nm limit the growth of martensites within the space between precipitates, leading to an inter-precipitate growth, while precipitates of size below 40 nm are imbedded in the growing martensitic plates, leading to an intra-precipitate growth. These predictions agree well with the experimental observations. Furthermore, the effects shape, size, spatial distribution, and volume fraction of the H-phase precipitates on various characteristics of the MT are quantified. The work is supported by DOE BES under Grant No. DE-SC0001258.
5:20 PM
Martensitic Transformation in a Rapidly-quenched Interstitial-free Steel using a Gleeble 3800 Thermo-mechanical Simulator: Mrinmoy Sinha1; Sadhan Ghosh1; B. Syed2; 1IIT Roorkee; 2R&D Division, Tata Steel, Jamshedpur, India
The strengthening of interstitial-free steel is the key focus of the present study. The samples have been soaked in the austenitic temperature domain for homogenization followed by furnace-cooling, air-cooling, and water-quenching in a Gleeble 3800 thermomechanical simulator. The outcome shows a dramatic increase in tensile strength along with a decent ductility in the water-quenched sample. As the reason, electron microscopy analysis has revealed the lath type morphology with high dislocation density. Further, the image-quality map, grain-boundary misorientation and Kurdjumov-Sachs orientation relationships with parent austenite confirm martensite in the interstitial-free steel by water-quenching, as the novel finding.
5:40 PM Cancelled
Critical Defect Concentration for Strain Glass Transition in Doped Ferroelastics: Chuanxin Liang1; Dong Wang1; Yunzhi Wang2; 1Xi'An Jiaotong University; 2The Ohio State University
The physical origin of strain glass is studied through thermodynamics and percolation theory by integrating atomistic and continuum simulations. The accurate local stress caused by point defect is calculated by molecular statics method, and an enforced stoichiometry and atomic localization function approach is used to bridge the atomistic scale and mesoscale. Based on this accurate atomistic scale simulations, our phase field simulations based on thermodynamics show that nano confinement formed by stress domains due to sufficient point defects concentration regulates the space of nucleation and growth of martensitic domains and turns the sharp first-order MT into a continuous SGT. A percolation criteria based on our simulations is proposed to predict the potential of strain glass in Ti50Ni50-xMx systems, which agrees quantitatively with the experimental observations. Our work not only uncovers the physical origin of strain glass transition, but also suggest a novel multiscale method to predict new glass systems.