A new phase in a rapidly solidified and consolidated NbAl 3 -1 Pct TiB 2 alloy
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I.
INTRODUCTION
A S the result of the continuing interest in the development of advanced high-temperature structural intermetallic materials and composites for aircraft services, a considerable amount of work has been focused on understanding the room and elevated temperature mechanical properties of intermetallic alloys based on aluminides. Recent studies have been directed at developing "dispersion-strengthened" intermetallic alloys using the principles of rapid solidification technology ( R S T ) . [1'2'3] The emphasis in this approach is to disperse a low volume fraction of stable second-phase particles uniformly in the matrix. NbA13 is one of the most extensively studied intermetallic materials due to its attractive high-temperature properties. However, NbAI3 is difficult to process by conventional ingot metallurgy due to its inherent brittleness, and powder metallurgy-based approaches appear to have potential in the processing of these alloys. The present study was conducted on an RS processed NbA13 alloy dispersion strengthened with TiB2 to examine its microstructural characteristics. The properties of the alloy have been described elsewhere.t4] II.
EXPERIMENTAL PROCEDURE
NbA13 alloy containing 1 wt pct TiB2 was prepared as prealloyed ingots from high-purity constituents by nonconsumable arc-melting process under an argon atmosphere. The ingots were repeatedly melted to ensure chemical homogeneity. The prealloyed NbAI3 and NbA13TiB2 ingots were rapidly solidified as metal-spun filaments using an advanced spinning technique, t51 The rapidly solidified filaments, 20- to 50-~m thick and 0.55-ram wide, were pulverized into powders (
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