Net Shape Manufacturing of Bulk Metallic Glass and Prediction of Glass Forming Ability

Abstract

Bulk Metallic Glass (BMG) possesses a variety of extraordinary properties including ultra high elastic limit and strength and has been applied in diverse fields such as industrial coatings, sporting foods, medical devices, defense and aerospace sectors. The cross-section thickness of a few millimeters for cast BMG alloy components limits their application to manufacturing structural components. However, continuing global efforts are underway to increase the critical part size cast with BMG alloys. There are two phases tot his project. Phase 1 investigates the feasibility of using suitable BMG alloys to manufacture a pivot assembly in an Airborne Gravity Gradiometer (AGG) via net shape manufacturing techniques. Success of Phase 1 will enable a quantum leap in the capabilities of the present day AGG devices to successfully and accurately scope the vast untapped mineral and petroleum resources globally. Requirements of high tolerances in the pivot assembly with very specific material properties and a net shape manufacturing route coupled with the lack of any database for BMG alloys were the inherent challenges. Suitable BMG alloys have been identified for this purpose and continued efforts are underway to manufacture the pivot assembly. Phase 2 of this project lays the foundation for a much needed tool to predict the Glass forming Ability of BMG alloys. This will enable to scientifically develop novel BMG alloys to suite specific application in lieu of the current ad-hoc development trends. A viable thermal model to understand the relationship between growth rate of solid phase and melt undercooling during uni-directional solidification coupled with a solidification model based on competitive growth principles have been developed. Novel experiment program and setup have been developed to verify these models.