Research

Computational Research Projects

CAREER: An Efficient First-Principles Method for Calculating Deformation Properties, Diffusivity, and Secondary Creep-Rate Behavior in BCC High-Entropy Alloys

This CAREER award supports computational research and educational activities with an aim to understand fundamental failure mechanisms in a new class of engineering alloys called high-entropy alloys (HEAs). HEAs are a relatively new class of engineering materials that show significant promise for replacing traditional engineering alloys, such as steel, in high temperature and load-bearing applications. HEAs are unique because they are typically composed of five elements in approximately equal proportions, whereas traditional engineering alloys, such as conventional steel, have one base alloying element (e.g. iron) which makes up at least 95% of the composition. Determining properties of HEAs using physics-based simulations, however, are challenging because of the large computational resources required to handle the multiple elements and atomic configurations of HEAs. The PI and her team will investigate an important mechanical property of HEAs, known as creep failure, which is the time-dependent and permanent deformation of a material under applied load or stress. A fundamental understanding of creep failure in these materials could potentially lead to the replacement of traditional engineering alloys with HEAs that could create faster, more fuel-efficient, and less costly machines.

Computational Resources

C. Hargather’s computational research laboratory has a 6-node, 160 compute node Supermicro SuperWorkstation Linux cluster running CentOS 7 as its operating system. The cluster runs the Vienna ab-initio Simulation Package (VASP), version 5.4.1, which will be the computational engine for the DFT work proposed in Thrust 1. The cluster also has Thermo-Calc version 2016b, which may be used to compare relevant DFT calculated properties of the systems being studied in Thrust 2. We have two Thermo-Calc databases: TCHEA1 (high entropy alloy database, v.1) and SSOL6 (solid solution database, v.6).

Experimental Research Projects

  1. Additive Manufacturing of Solid Composite Propellant Rocket Motors

Solid composite propellant rocket motors are traditionally fabricated using a cast and cure method with formulations that involve an oxidizer such as ammonium perchlorate (AP), a fuel such as aluminum (Al), and a binder such as hydroxyl-terminated polybutadiene (HTPB). In the present work, additive manufacturing techniques for manufacturing solid composite rocket motors are investigated.

  1. Development of a Pyrotechnic Initiator Ink

  2. Sensitivity and initiation testing of metal-perchlorate based propellants with epoxy binders

Experimental Resources

C. Hargather’s additive manufacturing lab has a custom built 3-axis rheology testbed for additive manufacturing of solid composite rocket propellant and other high viscosity slurries. For rheology, She has a Burrell Scientific Rheometer Model A-120 for extrusion rheometry and a Brookfield DV2T Viscometer with helipath stand. She also has 3 commercial additive manufacturing machines for polymers and desktop CNC machine, and injection molder, for other rapid prototyping needs.

Current Funding includes:

  • Sandia National Laboratories (SNL)

  • National Science Foundation (NSF)

  • Army Research Lab (ARL)

  • National Nuclear Security Agency (NNSA)