Compaction and characterization of mechanically alloyed nanocrystalline titanium aluminides

• Published in: Metallurgical and materials transactions. A, Physical metallurgy and materials science Physical metallurgy and materials science, 1997-02, Vol.28 (2), p.293-302
• Main Authors: SURYANARAYANA, C, KORTH, G. E, FROES, F. H
• Format: Article
• Language: English
• Subjects: Applied sciences; Cross-disciplinary physics: materials science; rheology; Exact sciences and technology; Materials science; Materials synthesis; materials processing; Metals. Metallurgy; Physics; Powder processing: powder metallurgy, compaction, sintering, mechanical alloying, and granulation
• ISSN: 1073-5623; 1543-1940
• DOI: 10.1007/s11661-997-0132-4

Blended elemental (BE) Ti-24 at.% Al-11 at.% Nb (Ti-24-11_) and Ti-55 at.% Al (Ti-55) powders and prealloyed (PA) Ti-24-11 powders were mechanically alloyed in a SPEX mill or an attritor. After SPEX milling for 10 h, the BE Ti-24-11 powder contained the B2/bcc phase, while the BE Ti-55 powder showed the presence of an amorphous phase. The PA Ti-24-11 powder containing the B2 phase showed a decrease of crystal size on milling. These powders were consolidated by hot isostatic pressing ("hipping"), Ceracon process, and dynamic methods. On compaction, the B2/bcc phase in the Ti-24-11 sample transformed to a mixture of the B2 and orthorhombic ("O") phases, while the amorphous phase in the Ti-55 powder crystallized to a mixture of the gamma -TiAl and alpha sub 2 -Ti sub 3 Al phases. The finest grain size in compacted material was obtained in the dynamically consolidated powder, and the grain size in the hot isostatic pressed ("hipped") powder became larger with the increasing hipping temperature.