2017 Technical Division Student Poster Competition: Light Metals Division (LMD) Graduate Students
Sponsored by: TMS Extraction and Processing Division, TMS Functional Materials Division, TMS Light Metals Division, TMS Materials Processing and Manufacturing Division, TMS Structural Materials Division
Program Organizers: TMS Administration

Monday 5:00 PM
February 27, 2017
Room: Hall B1
Location: San Diego Convention Ctr

SPG-19: Application of Computational Thermodynamics & Kinetics to Rare Earth Reduction in Magnesium Alloys: Kyle Fitzpatrick-Schmidt1; Danielle Cote1; Diran Apelian1; 1Worcester Polytechnic Institute
    Magnesium alloys are widely used in numerous applications due to their extremely low density. Through the addition of rare earth metals, the high temperature capabilities of magnesium alloys are increased by creation of thermally stable secondary phases. This research is focused on reducing the amount and number of rare earth elements used in these alloys, while simultaneously maintaining the high temperature capabilities and low density. Thermodynamic, kinetic, and strengthening mechanism models have been used to analyze the magnesium alloy EZ33A and seven new compositions with varied amounts of rare earths and additional elements. The theoretical analysis was followed by experimental investigation of the new alloy compositions.

SPG-20: Effect of Strontium and Calcium Concentration on Microstructure and in vitro Degradation Rate: David Christianson1; Hunter Henderson; Alex Wilson-Heid1; Michele Manuel; 1University of Florida
    Magnesium is an attractive choice for biomedical applications due to its potential to degrade safely in in vivo environments. Calcium and strontium are promising alloying additions because of their low toxicity levels. These elements form secondary phases that affect the rate of degradation through galvanic corrosion with the Mg matrix. Mg degradation forms H2 gas, so it is desirable to control the degradation rate of the implants to fit their desired applications. This study investigates the relationship between the as-cast microstructure and degradation rate (as measured in simulated body fluid) in a systematic review of the Mg-rich corner of Mg-Ca-Sr. Of particular interest is the effect that second phase contiguity has on degradation rate.

SPG-21: Feedstock Powder Analysis for Additive Manufacturing Applications: Caitlin Walde1; Danielle Cote1; Richard Sisson1; Victor Champagne2; 1WPI; 2US Army Research Laboratory
    Gas-atomized metallic powders are commonly used in additive manufacturing processes. While their bulk and post-process consolidated properties are widely studied, there is little research on the properties of the powders before processing. Understanding the powder characteristics before use in additive manufacturing could lead to fine-tuning properties of additively manufactured materials, as the consolidated material properties are often dependent on the feedstock powder properties. This research compares the properties of four gas atomized aluminum alloy powders to their wrought counterparts in an effort to gain a comprehensive understanding of feedstock powder properties to improve effectivity of additive manufacturing processes. Differential scanning calorimetry, x-ray diffraction, and microscopy techniques will be used.

SPG-22: Numerical Investigation on Gas Bubble Behaviors in Aluminum Reduction Cell with Slotted Anode: Meijia Sun1; Baokuan Li1; Jian-ping Peng1; 1Northeastern University
    In order to understand the gas bubble behaviors and interface fluctuation between bath and metal in a 300kA aluminum reduction cell with both slotted and traditional anodes. A three-dimensional (3D) mathematical model has been developed to analyze the transient three phases (gas, bath and metal) turbulent magnetohydrodynamics flow with the effect of electromagnetic field which is solved by the electrical potential method. Discrete particle model (DPM) is applied to track the motion of gas bubbles, and the volume of fluid (VOF) approach is employed to simulate the free surface. The result indicates that the gas removal rate increases with using the slotted anode. Moreover, the gas volume fraction and gas bubble coverage under the anode bottom are reduced. As a result, it is effective for the stability of bath-metal interface.

SPG-23: Orientation and Length Scale Effect in Deformation Mechanism in Pure Magnesium: Ali Khosravani1; Surya Kalidindi1; 1Georgia Institute of Technology
    In this work, the anisotropy of elastic and plastic properties of pure magnesium are investigated using spherical indentation stress strain analysis on grains of different orientations in a polycrystalline sample. The measurements show variations in indentation elastic modulus (Eind), indentation yield strength (Yind), and indentation hardening rate (Hind) as function of the grain lattice orientation. In addition, length scale effects were studied over wide range of indenter sizes: 1, 16, 100, and 500 µm (radius) on multiple grain orientations. This study provides new insights into slip and twin activities in plastic deformation of pure magnesium at different length scales.

SPG-24: Thermodynamic & Kinetic Model Application to Strengthening Mechanisms of Aluminum Alloys for Additive Manufacturing: Derek Tsaknopoulos1; Danielle Cote1; Richard Sisson1; Victor Champagne1; 1Worcester Polytechnic Institute
    While gas-atomized powder has become a staple feedstock material for additive manufacturing, detailed understanding regarding the mechanical properties of the raw material is needed for superior process modeling. Focusing primarily on the yield strength of the feedstock powder, various strengthening mechanisms are considered for the contributions from solid solution strengthening, grain size strengthening, precipitation, and dispersion mechanisms. These equations utilize the quantified kinetic and thermodynamic outputs from modeling software Thermo-Calc, JMatPro®, and TC-PRISMA. The data from these models coupled with the strengthening contributions progress into a strengthening model that represents the overall strengthening influence of each mechanism for specified gas-atomized powders. The effectiveness of this strengthening model is determined using thermal, optical, and mechanical characterization methods.