2021 Technical Division Student Poster Contest: SMD 2021 Technical Division Graduate Student Poster Contest
Program Organizers: TMS Administration

Monday 5:30 PM
March 15, 2021
Room: RM 9
Location: TMS2021 Virtual


Mechanical Behavior of Thermally Stable, Hierarchical Ni-Y Alloys: Shruti Sharma1; Samuel Moehring1; Saurabh Sharma1; Kiran Solanki1; Pedro Peralta1; 1Arizona State University
    Microstructure refinement and alloy additions are potential routes to increase the high temperature performance of existing metallic alloys. Nanocrystalline (NC) metallic alloys with immiscible second phases, e.g., Cu-10Ta, exhibit improvements over microstructurally unstable NC metals and their coarse-grained counterparts. However, matrices with higher melting points must be considered. Ni-Y alloys synthesized via arc-melting were studied for this purpose. Samples were heat-treated to study microstructural stability and characterized using WDS for local composition, SAXS for particle size distribution and spacing, and EBSD for local crystallography. Alloys had a stable, hierarchical microstructure with ultrafine eutectic of ~300 nm, dendritic arm spacing of ~10 µm and grain size ~200 μm. Uniaxial compression performed at 25 and 600 °C and room temperature hardness tests revealed that yield strength and microhardness of alloys with small amounts of Y (0.5-1wt%) were comparable to Ni-superalloys, due to the hierarchical microstructure and potential presence of nanoscale intermetallic precipitates.

Nano-mechanical Behavior of Advanced Structural Alloys: Nandita Ghodki1; Sundeep Mukherjee1; 1University of North Texas
    Bulk metallic glasses exhibited superior mechanical properties such as high strength, high hardness and good corrosion resistance which makes them attractive as potential materials for many applications in biomaterials, catalysis, etc. Nanoscale strain rate sensitivity of BMGs was investigated to understand the fundamentals of thermally activated deformation mechanism. Micro-pillar compression of structural alloys and coatings as a function of strain rate and temperature was investigated to understand the shear band activation and propagation mechanism at small length scales. Time and temperature dependent plastic deformation was investigated at nanoscale for the BMGs to explain relaxation and thermal softening effect.

Prediction and Testing of Hot Cracking Susceptibility during Local Melting in Binary and Multi Component Aluminum Alloys: Shubhra Jain1; 1Iowa State University
    Hot cracking is a widespread and severe defect during local melting, and it is clearly an important issue defining the alloy’s design capability during AM processing. Because of the nature of semi-solid mushy zone and complexity of the interactive mechanisms involved at the microstructural scale, several criteria have been developed to predict hot cracking. Since there is no ultimate controlling factor, these criteria do not fully predict crack susceptibility with respect to all possible metallurgical and thermo-mechanical factors. Likewise, testing and quantification of hot cracking susceptibility is not yet standardized and there is a critical need for a reliable test method. The work presented here involves the use of a new laboratory-scale localized melting method for rapid quantification of the in-build crack susceptibility. The results are analyzed in combination with direct hot cracking predictors obtained from thermodynamic and micro-segregation models complemented with relevant comparisons are made with reported alloy performance.

Solidification and Defects Structure Evolution in Metal Additive Manufacturing via Molecular Dynamics Simulations: Gurmeet Singh1; Veera Sundararaghavan1; 1University of Michigan
    Additive manufacturing is now being routinely used in industry to build metal parts due to the flexibility it allows in part design. In this work, we look at additive manufacturing of a single crystal using molecular dynamics simulation where a melt pool is incrementally added to a periodic structure to build a column from the bottom up. Embedded atom model potential is utilized in the atomic simulations and the evolution of different types of structures and defects in a layer-by-layer manner during the deposition of material is studied. Preliminary studies show that the percentage of defect-free content for additively manufactured copper converges when a sufficient number of layers is reached. Slower cooling rates improve the FCC content for all the layers; however, the benefits of slow cooling reduce beyond a point. The influence of substrate temperature and nano-inclusions are also investigated for defect evolution in the additive column.