Aluminum Beryllium Composites Produced by Rapid Solidification (Metastable Equilibrium, Modulus Hardening, Liquid Immiscibility)

Al-Be alloys, 4.4-20 at.% Be in composition, have been rapidly solidified by laser surface remelting and melt-spinning. Microstructures of uniform dispersions of spherical Be particles (10-15 nm in diameter), randomly dispersed in an Al matrix were produced for compositions 5-8 at.% Be. Two crystal forms of Be were observed in these solidified microstructures; equilibrium cph and metastable bcc. A cubic lattice parameter of 0.25 (+OR-) 0.02 nm was experimentally determined by electron diffraction for the metastable bcc Be. A mechanism for the formation of the microstructure was described by a metastable phase diagram involving a liquid miscibility gap. Thermal decomposition of the rapidly solidified microstructure resulted in a prism-rod morphology of cph Be particles with 8 crystallographic orientations observed.

Name thesis:degree_name

Ph.D.

Level thesis:degree_level

Dissertation

Discipline thesis:degree_discipline

Metallurgical Engineering

Grantor

University of Illinois at Urbana-Champaign

Year dc:date

2014

Author dc:creator

• Van Aken, David Carlton

• Engineering, Metallurgy

Identifier

(UMI)AAI8701644

OAI identifier oai:identifier

oai:www.ideals.illinois.edu:2142/71839