Mechanical Behavior of Nanostructured Materials: Mechanical Milling
Sponsored by: TMS Materials Processing and Manufacturing Division, TMS Structural Materials Division, TMS: Mechanical Behavior of Materials Committee, TMS: Nanomechanical Materials Behavior Committee
Program Organizers: Xinghang Zhang, Purdue University; Yuntian Zhu, North Carolina State University; Joseph Poon, University of Virginia; Suryanarayana Challapalli, University of Central Florida; Enrique Lavernia, University of California, Irvine; Haiyan Wang, Texas A&M University

Monday 2:00 PM
February 27, 2017
Room: 30D
Location: San Diego Convention Ctr

Funding support provided by: AJA International; Hysitron Inc.

Session Chair: C. Suryanarayana, University of Central Florida; Pascal Bellon, University of Illinois, Urbana-Champaign; Tongde Shen, Yanshan University

2:00 PM  Invited
Processing and Properties of Nanostructured Metallic Systems: John Lewandowski1; 1Case Western Reserve University
    Various collaborative works with a number of different organizations will be reviewed to demonstrate the unique processing approaches and microstructure/property combinations possible for nanostructured metallic systems. In the first case, the extrusion of amorphous Al-Ni-X powders was utilized to create nanostructured composites with high strength/modulus and high cycle fatigue resistance at both room temperature and elevated temperature. In the second case, the unique stress state provided by hydrostatic extrusion was utilized to create nano-ODS steel with improved performance. The final example relates to the creation of bulk high density metallic nanostructure Ni-based alloys created via SPS.

2:25 PM  
Dependence of Shear Mixing on Alloy Properties: A Study on Cu-X-Mo Ternary Alloys: Nisha Verma1; Nirab Pant1; John Beach1; Pascal Bellon1; Robert Averback1; 1University of Illinois at Urbana-Champaign
    Forced chemical mixing under severe plastic deformation in highly immiscible binary alloys is at present poorly understood. On the one hand, precipitate sizes in these alloys can be reduced to nanometers during shear mixing at low temperatures and solubilities gets greatly enhanced, but on the other hand, they do not homogenize. One difficulty in developing an understanding of this behavior derives from the fact that several materials properties are involved in the shear mixing of binary alloys, and in binary systems they cannot be systematically controlled. In the present work, we examined dilute ternary Cu-X-Mo alloys, where X = Ag or Ni. By varying the concentration and thermochemical properties of X, we systematically varied the heat of mixing and relative elastic properties of Mo in the alloy. The precipitates sizes and solubilities of Mo during ball milling or HPT were followed by TEM and x-ray diffraction. The results are compared with model MD simulations.

2:45 PM  Invited
Mechanical Alloying by Severe Plastic Deformation: Reinhard Pippan1; Andrea Bachmaier1; Lisa Kraemer1; Pradipta Ghosh1; Karoline Kormout1; Timo Mueller1; Anton Hohenwarter2; Oliver Renk1; 1Erich Schmid Institute of Materials Science, Austrian Academy of Sciences; 2Montanuniversität Leoben
    Severe plastic deformation (SPD) is as well established technique to generate ultrafine grained or nanocrystalline materials from originally coarse grained single phase materials. In the last ten years it has been shown that severe plastic deformation of multiphase materials or composites can be used to generate nanocomposites, supersaturated solid solutions or amorphous materials. These studies indicate that SPD can generate microstructures similar to classical mechanical alloying in a well defined way. The presentation will give an overview of the different possibilities of the used starting materials (multiphase alloys, composites, mixture of metal powders or metal-metallic glass powders, metal polymer powders, etc.), a comparison of SPD technique to obtain mechanical alloying and the processing parameters which effect the final microstructure after processing. Limitations and possible solutions to overcome the application of SPD techniques to generated homogenous mechanical alloyed materials will be discussed

3:10 PM  
Nanostructured Ferritic Steels: Synthesis, Microstructure and Mechanical Properties: Somayeh Pasebani1; Indrajit Charit1; Yaqiao Wu2; Jatuporn Burns2; James Cole3; Darryl Butt2; 1University of Idaho; 2Boise State University; 3Idaho National Laboratory
    It is a great honor to present a talk in the symposium honoring Professor Carl Koch who has made many seminal contributions to our understanding of nanocrystalline materials. In this work, an elemental powder mixture with a nominal composition of Fe-14Cr-1Ti-0.3Mo-0.5La2O3 (wt.%) was mechanically alloyed for 0-20 h and subsequently consolidated using spark plasma sintering (SPS) under vacuum at 850-1050 oC for 7-45 min. The effect of process parameters on the densification behavior was investigated. The density of the specimens was measured via Archimedean principle, and mechanical properties via microhardness, shear punch and compression testing. Microstructural studies of the sintered specimens using TEM and EBSD revealed bimodal grain structure with a combination of nanocrystalline grains and ultrafine grains. In addition to Cr-rich particles, La-Ti-O based nanoclusters with high number density were noted to form. Mechanical properties of the developed alloys are discussed in terms of the operating strengthening mechanisms.

3:30 PM Break

3:50 PM  Invited
Microstructures and Mechanical Properties of Nanostructured and Ultrafine Grained Al Alloy and Cu Matrix Nanocomposites Fabricated by Thermomechanical Powder Consolidation: Deliang Zhang1; Dengshan Zhou1; Xun Yao2; Jiamiao Liang2; Wei Zeng2; Charlie Kong3; Paul Munroe3; 1Northeastern University; 2Shanghai Jiao Tong University; 3University of New South Wales
    Nanostructured powders were made by high energy mechanical milling of mixtures of Al alloy chips or Cu powder and SiC or Al2O3 nanoparticles. The mechanically milled powders were consolidated by powder compact extrusion to fabricate bulk nanostructured or ultrafine grained Al alloy and Cu matrix nanocomposites. The ceramic nanoparticles play a critical role in controlling the recrystallization and grain growth during extrusion. The large area of grain boundaries and Al/SiC interfaces work as effective sinks for vacancies during quenching, and thus prevent formation of a large number density of precipitates for age hardening. Grain boundary strengthening makes a major contribution to the strength, and it is still not clear whether the ceramic nanoparticles, especially those at the grain boundaries significantly contribute to the strengthening. The state and strength of interparticle boundaries have significant influence on the tensile ductility and fracture behavior of this type of materials.

4:15 PM  
Mechanical Properties of Aluminum Composites with Nano Alumina Reinforcement: William Harrigan1; 1Gamma Technology, LLC
    Gamma Technology has developed and patented a process to introduce nano size alumina particles into aluminum alloys. This process has been scaled from a laboratory process to a prototype process and will be scaled to 100 kg samples during 2016. This process does not require expensive procedures and will deliver nano particle reinforced aluminum at a reasonable cost. The room temperature tensile strength for the 1100 matrix composite went from 90 MPa for the unreinforced matrix to 255MPa for 5% nano particle composite. The tensile elongation for the 5 percent composite is 18 percent. The elevated temperature tensile strength at 375°C increased from 14 MPa to 100 MPa for the composite containing 10 percent nano particles. This talk will detail the work done this year to introduce the nano particles to other matrix alloys with increased solid solution strengthening and with precipitation strengthening.

4:35 PM  Invited
Ultrahigh-strength Nanostructured Magnesium Alloys via Mechanical Alloying: Suveen Mathaudhu1; 1University of California Riverside
    Magnesium alloys have seen limited application in part to their low strength compared to conventional structural alloys, such as Al-, Ti- and Fe-based materials. While the effects of nanostructuring on strength have been well-studied in the case of the latter systems, opportunities yet remain to improve the strength of Mg-alloys via this approach. In this presentation, we will present some of the initial studies performed in collaboration with Prof. Koch, and inspired by his pioneering mechanical alloying methodologies, on the synthesis of nanostructured Mg-alloys. Behaviors distinct from their course-grained counterparts will be reported along with the major findings and resultant technological opportunities.

5:00 PM  
Suppressing Oxide Nanoparticle Coarsening and Cu Nanograin Growth in Nanostructured Cu Matrix Nanocomposites by Adding Ti: Dengshan Zhou1; Wei Zeng2; Charlie Kong3; Paul Munroe3; Deliang Zhang1; 1Northeastern University; 2Shanghai Jiao Tong University; 3The University of New South Wales
    Suppressing oxide nanoparticle coarsening during powder consolidation is crucial for fabricating bulk nanostructured metal matrix nanocomposites with excellent mechanical and physical properties via powder metallurgy routes. It has shown that alloying element can significantly improve the thermal stability of oxide nanoparticles in oxide dispersion-strengthened (ODS) metals, so we investigated the effectiveness of minor Ti addition on the suppression of Al2O3/Y2O3 nanoparticle coarsening and Cu nanograin growth during annealing mechanically milled nanostructured Cu-5vol.%Al2O3/Y2O3 nanocomposite powder particles. For the milled powder sample annealed at 700oC or 900oC for 1 hour, energy dispersive spectrometry (EDS) analysis revealed that the doped Ti atoms diffused into the Al2O3 or Y2O3 nanoparticles to form Ti-containing nanoparticles, which are more stable than those corresponding Ti-free nanoparticles. Such thermally stable Ti-rich complex nanoparticles effectively retarded the migration of Cu grain boundaries during annealing, inhibiting the growth of Cu nanograins.

5:20 PM  
Achieving Enhanced Room Temperature Ductility in Bulk Nanostructured Mg: Xin Wang1; Lin Jiang1; Dalong Zhang1; Enrique Lavernia1; Julie Schoenung1; 1University of California, Irvine
    Insufficient ductility is a major obstacle to the increased application of Mg as a lightweight structural material. In the present study, bulk nanostructured Mg was fabricated by means of powder metallurgy via cryogenic ball milling and subsequent consolidation by spark plasma sintering (SPS). As-sintered samples were compression tested at room temperature at a strain rate of 10-3 s-1. A large strain of over 100% and a yield strength of ~160 MPa were achieved. Mechanisms responsible for the exceptional ductility were further investigated by exploring the microstructure and microtexture of these samples. TEM observations revealed a bimodal grain size distribution consisting of submicron sized coarse grains distributed in a nanocrystalline matrix with an average grain size of ~70 nm. Microtexture analysis by transmission Kikuchi diffraction indicated randomized orientations of the nanograins. Our results suggest effective grain refinement and texture randomization are important for enhanced ductility in Mg.