Tensile Behavior of Nb7.5Ta for Heat-Exchanger Applications

Document Type

Conference Proceeding

Publication Date

7-22-2007

Publication Title

ASME 2007 Conference Proceedings

Publisher

ASME

Volume

6

First page number:

395

Last page number:

399

Abstract

Hydrogen generation using sulfur-iodine cycle involves the formation and decomposition of sulfuric acid and hydrogen iodide (HI). The decomposition of HI has been proposed to occur at a maximum temperature of 400°C. Nb7.5Ta has been identified as a candidate structural material for use in heat-exchanger during the decomposition of HI. This paper presents the results of tensile testing at temperatures ranging from ambient to 400°C. A gradual drop in tensile strength was noted with increasing temperature. Reduced failure strain was observed at temperatures up to 300°C, which is known to be associated with the occurrence of dynamic strain aging (DSA). Since the concentration of precipitate and dislocations can influence the DSA behavior of susceptible materials, efforts are in progress to characterize dislocations using transmission electron microscopy. All tested specimens exhibited ductile failures, characterized by dimples.

Keywords

Heat exchangers – Materials; High temperatures; Hydrogen as fuel; Niobium-tantalum alloys – Fatigue; Strains and stresses; Structural failures

Disciplines

Heat Transfer, Combustion | Materials Science and Engineering | Mechanical Engineering | Mechanics of Materials | Metallurgy

Language

English

Comments

From: ASME 2007 Pressure Vessels and Piping Conference, San Antonio, Texas, USA, July 22–26, 2007

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