Ultrafine-grained and Heterostructured Materials (UFGH XII): Processing & Microstructure
Sponsored by: TMS: Shaping and Forming Committee
Program Organizers: Penghui Cao, University of California, Irvine; Xiaoxu Huang, Chongqing University; Enrique Lavernia, Texas A&M University; Xiaozhou Liao, University of Sydney; Lee Semiatin, MRL Materials Resources LLC; Nobuhiro Tsuji, Kyoto University; Caizhi Zhou, University of South Carolina; Yuntian Zhu, City University of Hong Kong

Wednesday 8:30 AM
March 2, 2022
Room: 262A
Location: Anaheim Convention Center

Session Chair: David Field, Washington State University; Suveen Mathaudhu, Colorado School of Mines; Nobuhiro Tsuji, Kyoto University

8:30 AM  
Influence of High-pressure Torsion-induced Strain on Electrical Conductivity and Wear Resistance: Evander Ramos1; Takahiro Masuda2; Zenji Horita2; Suveen Mathaudhu1; 1University of California-Riverside; 2Kyushu University
    High-pressure torsion (HPT) is known to impart strain with radial inhomogeneity, potentially creating heterogeneous microstructures and properties. Hardness testing and microscopy are widely used to characterize properties at specific locations throughout the disc, thus facilitating correlation of their evolution with strain. Alternatively, properties like electrical conductivity and wear resistance are measured across large areas, and thus wide ranges of strains. Here, electrical conductivity and wear resistance of different sections of HPT-processed discs are characterized with specific regard to local strain. For conductivity, discs were cut into a spiral pattern to obtain a uniform cross section with monotonically increasing strain, thereby enabling a more precise study of electrical properties at various strains. Additionally, linear reciprocating wear tests were conducted at different regions of the disc and in different directions in relation to the HPT processing. Good agreement is found between these results and other severe plastic deformation literature.

9:00 AM  
Designed Heterostructures in AZ31 Using Linear Corrugated Straightening: Mueed Jamal1; Gunnar Blaschke1; David Field1; 1Washington State University
    Linear corrugated straightening is a method by which heterostructures can be created to meet specific design requirements. EBSD analysis shows that microstructures in plate material can easily be created with alternate regions of large grain and small grain structures as well as differing crystallographic textures. Both of these features result in improved or retained elongation and increased strength as demonstrated in AZ31. Finite element based modeling is shown to be useful in designing the process for the desired microstructure.

9:20 AM  Invited
Superplastic Response of Accumulatively Roll-bonded Aluminum Sheets: Kester Clarke1; Amy Clarke1; Brady McBride1; 1Colorado School of Mines
    Accumulative roll bonding (ARB) is a severe plastic deformation technique used to produce ultrafine grained material. Materials processed by ARB are attractive as they exhibit enhanced strength at ambient temperatures due to Hall-Petch strengthening. Some alloys also demonstrate low temperature superplasticity, which has the potential to decrease cycle time and cost in superplastic forming operations. Lower temperature superplasticity behavior can be quite sensitive to microstructure and processing conditions, and microstructural development during forming operations can have significant effect on formability and post-forming properties. ARB is necessarily a directional processing pathway, so considerations of texture development and strain path are also important.

9:50 AM  
Breaking the Strength-toughness Barrier through Impact-induced Recrystallization of Single-crystal Silver Microcubes: Claire Griesbach1; Jizhe Cai1; Ramathasan Thevamaran1; 1University of Wisconsin Madison
    As typically mutually exclusive properties, optimizing both strength and toughness requires exploitation of complementary deformation mechanisms provided by different structural heterogeneities. We show that nanostructural changes induced through impact of single-crystal silver microcubes lead to a two-fold improvement in both strength and toughness. Single-crystal silver microcubes are impacted onto a rigid target at ~400 m/s using a laser-induced projectile impact testing (LIPIT) apparatus and undergo extensive recrystallization, forming a gradient-nano-grained (GNG) structure. Stress-strain curves obtained through in situ SEM microcompression testing of pillars FIB-milled from the impacted cubes show ultra-high hardening rates, high yield strengths, and large compressive toughness. The impacted cubes outperform both single-crystal microcubes and bulk polycrystalline silver, boasting superior strength and toughness. The improvement in both properties is attributed to a combination of inter- and intragranular plasticity mechanisms elicited through the spatial gradient of nanograins to coarse grains representative of a GNG structure.