A transmission electron microscopy and three-dimensional atom probe study of the oxygen-induced fine microstructural features in as-sintered Ti-6Al-4V and their impacts on ductility

作者：Yan M; Dargusch M S; Ebel T; Qian M^*

来源：Acta Materialia, 2014, 68(15): 196-206.

DOI：10.1016/j.actamat.2014.01.015

• Titanium alloys
• Atom probe tomography
• Oxygen

Recent systematic experimental studies involving the benchmark Ti-6Al-4V alloy fabricated from powder have established that there exists a critical level of oxygen around 0.33 mass%, beyond which the tensile ductility of the alloy drops dramatically until reaching total brittleness. To understand the fundamental mechanisms behind this critical oxygen content, three-dimensional atom probe tomography, transmission electron microscopy and other analytical means have been used to identify and characterize the fine microstructural changes induced by the increased oxygen content beyond the critical level. Three fine microstructural features were identified in as-sintered Ti-6Al- 4V when the interstitial oxygen content was increased from 0.25 mass% to 0.49 mass%. These are: (i) the formation of fine acicular alpha precipitates in the beta phase; (ii) the formation of alpha(2)-type (Ti3Al) nanometric clusters in the alpha matrix; and (iii) grain boundary alpha-beta-alpha-layered structures between the alpha grains. The impacts of these microstructural changes on the tensile ductility are discussed.

• 出版日期2014-4