The Impact of Partial Crystallization on the Permeation Properties Bulk Amorphous Glass Hydrogen Separation Membranes
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The Impact of Partial Crystallization on the Permeation Properties Bulk Amorphous Glass Hydrogen Separation Membranes Kyle S. Brinkman1 Elise B. Fox1, Paul Korinko1, Thad Adams1 and Arthur Jurgensen2 1 Materials Science and Technology Directorate, Savannah River National Laboratory (SRNL) Aiken, SC 29808, U.S.A. 2 Analytical Development, Savannah River National Laboratory (SRNL) Aiken, SC 29808, U.S.A.
ABSTRACT It is recognized that hydrogen separation membranes are a key component of the emerging hydrogen economy. A potentially exciting material for membrane separations are bulk metallic glass materials due to their low cost, high elastic toughness and resistance to hydrogen “embrittlement” as compared to crystalline Pd-based membrane systems. However, at elevated temperatures and extended operation times structural changes including partial crystallinity may appear in these amorphous metallic systems. A systematic evaluation of the impact of partial crystallinity/devitrification on the diffusion and solubility behavior in multi-component Metallic Glass materials would provide great insight into the potential of these materials for hydrogen applications. This study will report on the development of time and temperature crystallization mapping and their use for interpretation of “in-situ” hydrogen permeation at elevated temperatures. INTRODUCTION The development of metallic glasses in bulk form had led to a resurgence of interest into the utilization of these materials for a variety of applications. A potentially exciting application for these bulk metallic glass (BMG) materials is their use as composite membranes to replace high cost Pd/Pd-alloy membranes for enhanced gas separation processes. One of the major drawbacks to the industrial use of Pd-Pd/alloy membranes is that during cycling above and below a critical temperature an irreversible change takes place in the palladium lattice structure which can result in significant damage to the membrane. Furthermore, the cost associated with Pd-based membranes is a potential detractor for their continued use and bulk metallic glass alloys offer a potentially attractive alternative. Several BMG alloys have been shown to possess high permeation rates comparable to those measured for pure Pd metal[1, 2]. Both of these properties- high permeation and high strength/toughness potentially make these materials attractive for gas separation membranes that could resist hydrogen “embrittlement”. However, a fundamental understanding of the relationship between partially crystalline “structure”/devitrification and permeation/embrittlement in these BMG materials is required in order to determine the operating window for separation membranes and provide additional input to material synthesis community for improved alloy design. This project aims to fill the knowledge gap regarding the impact of crystallization on the permeation properties of metallic glass materials.
EXPERIMENT Metallic glass samples with a nominal thickness of 25 microns in 2 inch wide ribbons were p
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