Ultrafine-grained and Heterostructured Materials (UFGH XI): Processing & Property
Sponsored by: TMS Materials Processing and Manufacturing Division, TMS: Mechanical Behavior of Materials Committee
Program Organizers: Caizhi Zhou, University of South Carolina; Megumi Kawasaki, Oregon State University; Enrique Lavernia, University of California, Irvine; Terry Lowe, Colorado School of Mines; Suveen Mathaudhu, Colorado School of Mines; Ruslan Valiev, UFA State Aviation Technical University; Yuntian Zhu, City University of Hong Kong
Thursday 8:30 AM
February 27, 2020
Room: Carlsbad
Location: Marriott Marquis Hotel
Session Chair: Huajian Gao, Brown University; Moara Castro, Slovak Academy of Sciences; Megumi Kawasaki, Oregon State University; Caizhi Zhou, Missouri University of Science and Technology
8:30 AM
Transition from Source- to Stress-controlled Plasticity in Nanotwinned Materials below a Softening Temperature: S. Mohadeseh Taheri-Mousavi1; Haofei Zhou2; Guijin Zou2; Huajian Gao2; 1Massachusetts Institute of Technology; 2Brown University
Nanotwined metals are interesting for structural applications as they exhibit simultaneous high strength and ductility. However, little is known about the temperature dependency of such unique mechanical properties. Atomistic simulations and theoretical modeling of nanotwinned (nt) Pd and Cu systems have led to a discovery that there exists a softening temperature, below which the material hardens continuously as the twin thickness is reduced (as in nt-ceramics), while above which the strength first increases and then decreases, exhibiting a maximum strength and a hardening to softening transition at a critical twin thickness (as in nt-Cu). This important phenomenon has been attributed to a transition from source- to stress-controlled plasticity below the softening temperature, and suggests that different hardening behaviors may exist even in the same nt-material depending on the temperature and that at a given temperature different materials could exhibit different hardening behaviors depending on their softening temperature.
8:50 AM
Tailoring Strength of 6082 Aluminium Alloy via Combination of Rolling and Heat Treatment: Witold Chrominski1; Malgorzata Lewandowska1; 1Warsaw University of Technology
Heat treatable 6082 aluminum alloy was subjected to several complex thermo-mechanical procedures including variations of rolling, accumulative roll bonding and heat treatment. The intention was to produce microstructure which will benefit from the combination of work- and precipitation strengthening. It was found that careful design of deformation route must be undertaken since non-cell forming alloy suppress precipitation due to relatively uniform distribution of dislocations after the rolling. In such a situation, dislocations attract solutes which cannot form strengthening phases. For this reason, a changes of rolling directions together with an interop heating were applied to promote low angle grain boundary formation instead. Strengthening curves course was altered when compared to undeformed material which indicate changes in precipitation occurrences. Combined EBSD and TEM investigation was performed to understand these variations in selected samples.
9:10 AM
Bulk nc-Dissolvable Alloys Enable Design of Retrievable Sensors for Oil & Gas: Ting Roy1; Indranil Roy2; Ram Shenoy2; Jing Zhou3; 1SET Laboratories; 2WellDiver; 3Rice University
Advent of water reactive or dissolvable materials and nanostructured alloys, enabling engineering of high strength, corrosion resistant structural materials with tailored specific gravity and with an intelligent combination of micro-electro-mechanical system (MEMS) sensor devices, mechanism to assess “Corrosion and Environmentally Assisted Cracking (EAC)” of oilfield alloys under live reservoir conditions is now possible. Our sensors facilitate testing at the production zone and not in a simulated autoclave environment, providing much needed data to make judicious materials selection for target environment without assumptions and extrapolations. Here we present method to deploy retrievable sensor packages in wellbore, wherein the gauge carrier is (1) made from bulk nanomaterial (2) has tailored specific gravity (3) ultra-high strength; as such can withstand greater than 10,000 psi collapse with wall thickness of ~ 1mm (4) can be corrosion resistant (stemming from customer requirement) (5) allows the retrieval of the sensor package aided by buoyant forces.
9:30 AM Cancelled
Heterogeneous Materials under Shear: Interlinking Surface Deformation Mechanisms and Friction: Xiang Chen1; Zhong Han2; Xiuyan Li2; Christian Greiner3; Peter Gumbsch3; Ke Lu2; 1Nanjing University of Science and Technology; 2Institute of Metal Research, Chinese Academy of Sciences; 3Karlsruhe Institute of Technology
The energy dissipated in a metallic frictional contact is largely converted into surface plastic deformation. Surface plastic deformation in turn brings about microstructural discontinuity and localized strain in the surface layer of homogeneous materials upon sliding, inevitably increasing their frictional resistance. Our recent investigations first demonstrated that a gradient nanostructured surface layer enables a significant reduction in friction and wear of metals and alloys, in contrast to their homogeneous counterparts. Surface structural evolution and stress field model unfold that shear-induced strain localization and microstructural instabilities are significantly mitigated through dislocation activity and grain boundary sliding in the gradient layers. In addition, design guidelines for heterogeneous materials with unprecedented low-friction lifetime are discussed based on interlinking surface deformation and friction.
9:50 AM Cancelled
Powder Metallurgy Fabrication, Microstructure and Mechanical Properties of Heterogeneous Structured Al: Deliang Zhang1; Lei Cao2; Jiamiao Liang2; 1Northeastern University; 2Shanghai Jiao Tong University
Bulk Al samples with a heterogeneous structure consisting of softer coarse grained Al regions and harder ultrafine grained regions which are also strengthened by dispersed Al3C4 and Al2O3 nanoparticles are fabricated by spark plasma sintering of a nanocrystalline Al powder followed by annealing or hot extrusion. The nanocrystalline Al powder was produced by high energy mechanical milling of an Al powder together with stearic acid powder as a process control agent. The Al bulk samples exhibited a relatively high yield strength together with excellent tensile ductility. The contributions of various strengthening mechanisms to the strength of the samples and the reasons for their good tensile ductility are analyzed, and the beneficial effect of heterogeneous structure on strength and tensile ductility is discussed.
10:10 AM Break
10:30 AM Invited
Heterogeneous High-entropy Alloys: A Review: Rui Feng1; Peter Liaw1; 1University of Tennessee
High-entropy alloys (HEAs), as a new class of metallic materials, have attracted increasing interests because of their outstanding mechanical performance. However, like traditional metal and alloys, the dilemma of the strength-ductility trade-off also exists in HEAs. In order to overcome this dilemma, the strategy of heterogeneous architecting has been extensively applied to HEAs for developing heterogeneous HEAs. Here, we review heterogeneous HEAs from the viewpoints of heterogeneous structures, processing techniques, mechanical properties, deformation mechanisms, and future perspectives. Towards a synergy of strength and ductility, the vision that guides the future development and research focuses of heterogeneous HEAs is provided.
10:50 AM
Ultra-uniformity in Nanocrystalline Materials: Implications from Generalized LSW Growth Theory and Validations: Yanhao Dong1; Hongbing Yang2; Jiangong Li2; I-Wei Chen3; Ju Li1; 1Massachusetts Institute of Technology; 2Lanzhou University; 3University of Pennsylvania
Nanocrystalline materials often show superior properties and are thus of great interest. Much has been discussed about ultrafine grain sizes, but little is known about ultra-uniformity, defined as grain size distribution narrower than predicted by the classical theory of Hillert. Here we provide a generalized growth theory unifying the mean-field solutions from Lifshitz, Slyozov, Wagner (LSW) and Hillert. For curvature driven grain growth, we find for growth exponent n >1 a steady-state size distribution that is analytically solvable. Significantly, the distribution narrows with increasing n, and experimental validation of this prediction is found in dense Al2O3 nanoceramics with an extremely uniform microstructure of 34 nm grain size. Reference: Yanhao Dong, I-Wei Chen. "Grain growth with size-dependent or statistically distributed mobility." arXiv preprint arXiv:1708.04092 (2017).
11:10 AM
Magnesium Based Composites Produced through HPT: Moara Castro1; Megumi Kawasaki2; Roberto Figueiredo1; 1Universidade Federal de Minas Gerais; 2Oregon State University
It is known that high pressure torsion (HPT) refines the grain structure of metallic based materials. This severe plastic deformation technique may also be used to consolidate metallic particles into a bulk disc. The present work reports the fabrication of magnesium based composites through the consolidation of magnesium particles with a second phase material. The effectiveness of the consolidation and the properties of the composite are evaluated. It is shown that this fabrication route provides the opportunity to produce composites without the need of heating the components and to obtain a refined structure in the metallic matrix.
11:30 AM
Ultrafine Grained 3003 Aluminium Alloy Plates with Low Anisotropy and the Capabilities to Deep Drawing: Malgorzata Lewandowska1; Marta Ciemiorek1; Witold Chrominski1; Lech Olejnik1; 1Warsaw University of Technology
3003 aluminium alloy plates were processed by Incremental ECAP up to 4 passes. The plates were evaluated in terms of microstructure, mechanical properties, anisotropy and formability. It is demonstrated that such a processing results in UFG microstructure with high fraction of high angle grain boundaries exceeding 60%. The plates exhibit in planar and through thickness isotropy which manifest by the independence of YS, UTS and rα -values on the testing direction and fairly uniform distribution of microhardness across thickness. The ability to deep drawing was also evaluated. showing that although the processed plates are slightly prone to wall thinning (typical for aluminum alloys), they are resistant to earing formation, which is one of the main technological problem in deep drawing. The combination of isotropic parameters, enhanced mechanical strength and suitable ability to deep drawing may yield attractive products with a considerable potential for further forming.
11:50 AM Cancelled
Searching for the Optimized Design in Heterogeneous Structure: Jie Pan1; Yan Lin1; Ruqing Cao1; Xiaoyi Cuan1; Yunli Lu1; Yi Li1; 1Institute of Metal Research, Chinese Academy of Sciences
Architecting heterogeneous structure has been adopted as a promising design strategy for evading the strength–ductility trade-off of structural materials. However, how to control microstructure and optimize their mechanical properties still remain challenging. In this work, the deformation behaviors of two typical heterostructured materials (i.e., gradient and layered materials) were systematically investigated, in contrast to the corresponding homogeneous materials. Mechanical testing revealed that optimum mechanical properties can be achieved by tailoring the profile of grain size distribution or layer thickness, where the strength and ductility of gradient and layered materials were both simultaneously enhanced, compared with the homogenous counterpart. This extra elongation accompanied by an increasing strength was rarely reported previously. It had been found the interplay between the various regions (e.g. hard and soft regions) played an important role in strain delocalization during plastic deformation. Meanwhile, the corresponding microstructural changes and underlying deformation mechanism are also further investigated.