Microstructural investigation of a rapidly solidified Ti-6Al-4V-1B-0.5Y alloy

Autor: L. Chandrasekaran, Z. Fan, C. M. Ward-Close, A. P. Miodownik
Rok vydání: 1995
Předmět:
Zdroj: Journal of Materials Science. 30:1653-1660
ISSN: 1573-4803
0022-2461
DOI: 10.1007/bf00351593
Popis: A Ti-6Al-4V-1B-0.5Y (wt%) alloy has been prepared by consolidation of the melt-spun alloy fibres. The microstructures of the melt-spun fibre and the consolidated alloy were examined by different techniques. It was found that in the consolidated alloy, titanium boride and yttrium oxide particles have a refined particle size and a uniform distribution in the α(+β) matrix compared with the microstructure of the same alloy obtained by conventional ingot metallurgy. The boride phase in the consolidated alloy mainly has a needle-shaped morphology and has been identified by electron diffraction to be orthorhombic TiB with a B27 structure, while the yttrium oxide has a cuboidal morphology and has been identified as bcc Y2O3. Detailed TEM examination also revealed that yttrium addition has a strong influence on the TiB morphology by comparing the microstructures of Ti-6Al-4V-1B alloys with and without yttrium addition. Under similar processing conditions, the TiB phase in the consolidated alloys without yttrium addition mainly has a nearly equiaxed morphology with a finer particle size, while the TiB phase in the consolidated alloy with yttrium addition will mainly have a needle-shaped morphology. This effect of yttrium addition on the TiB morphology has been discussed in terms of heterogeneous nucleation and the reduced undercooling.
Databáze: OpenAIRE
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