Precipitation of ordered {alpha}{sub 2} phase in Ti-6-22-22 alloy

Journal Article · Mon Aug 10 00:00:00 EDT 1998 · Acta Materialia

DOI:https://doi.org/10.1016/S1359-6454(98)00158-X· OSTI ID:651088

Zhang, X D; Wiezorek, J M.K.; Baeslack, III, W A; Fraser, H L ^[1]; Evans, D J ^[2]

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1. Ohio State Univ., Columbus, OH (United States)
2. AFRL/MLLM, Dayton, OH (United States). Materials and Manufacturing Directorate

Microstructural characterization of Ti-6Al-2Cr-2Mo-2Sn-2Zr (Ti-6-22-22) after various heat treatments has been performed using optical microscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM), and high resolution electron microscopy (HREM). The presence of very fine {alpha}{sub 2} precipitates has been detected by electron diffraction in conventionally heat treated samples. The {alpha}{sub 2} precipitates were observed within the {alpha} matrix of the triplex heat treated materials and also in samples cooled from the {beta} phase field with cooling rates of less than 5.5 C/s. It was found that the {alpha}{sub 2} precipitates were homogeneously distributed within the {alpha} phase with sizes of about 1--2 nm. Long time ageing at 650 C for 1,000 h stabilized the {alpha}{sub 2} precipitates which grew to 5--10 nm in diameter and 20--50 nm in length. Structural stability of the {alpha}{sub 2} precipitates has been discussed in terms of chemical composition and lattice mismatch between {alpha}{sub 2} precipitates and the {alpha} matrix.

• OSTI ID: 651088
• Journal Information: Acta Materialia, Vol. 46, Issue 13; Other Information: PBD: 10 Aug 1998
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
PHASE STUDIES
TITANIUM BASE ALLOYS
HEAT TREATMENTS
MICROSCOPY
PRECIPITATION
CHEMICAL COMPOSITION