Microstructural Evolution during Pressureless Sintering of Blended Elemental Ti-Al-V-Fe Titanium Alloys from Fine Hydrogenated-Dehydrogenated Titanium Powder

A comprehensive study was conducted on microstructural evolution of sintered Ti-Al-V-Fe titanium alloys utilizing very fine hydrogenation-dehydrogenation (HDH) titanium powder with a median particle size of 8.84 μm. Both micropores (5-15 μm) and macropores (50-200 μm) were identified in sintered tit...

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Bibliographic Details
Published in:Metals (Basel ) 2017-08, Vol.7 (8), p.285
Main Authors: Yu, Changzhou, Cao, Peng, Jones, Mark
Format: Article
Language:English
Subjects:
Alloying elements
Dehydrogenation
Densification
Evaporation
Evolution
Ferrous alloys
Hydrogenation
Loose powder sintering
Macroporosity
Mechanical properties
Microporosity
microstructural evolution
Oxygen content
powder metallurgy
sintering
Titanium alloys
Titanium base alloys
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Summary:A comprehensive study was conducted on microstructural evolution of sintered Ti-Al-V-Fe titanium alloys utilizing very fine hydrogenation-dehydrogenation (HDH) titanium powder with a median particle size of 8.84 μm. Both micropores (5-15 μm) and macropores (50-200 μm) were identified in sintered titanium alloys. Spherical micropores were observed in Ti-6Al-4V sintered with fine Ti at the lowest temperature of 1150 °C. The addition of iron can help reduce microporosity and improve microstructural and compositional homogenization. A theoretical calculation of evaporation based on the Miedema model and Langmuir equation indicates that the evaporation of aluminum could be responsible for the formation of the macropores. Although reasonable densification was achieved at low sintering temperatures (93-96% relative density) the samples had poor mechanical properties due mainly to the presence of the macroporosity and the high inherent oxygen content in the as-received fine powders.
ISSN:2075-4701
2075-4701
DOI:10.3390/met7080285