Journal
JOURNAL OF ALLOYS AND COMPOUNDS
Volume 616, Issue -, Pages 483-491Publisher
ELSEVIER SCIENCE SA
DOI: 10.1016/j.jallcom.2014.07.130
Keywords
Metals and alloys; TEM; Microstructure; Phase transformation
Categories
Funding
- National Basic Research Program of China (973 Program) [2011CB605501]
- National Natural Science Foundation of China [51171015, U1204508]
Ask authors/readers for more resources
High Nb containing TiAl (Nb-TiAl) alloys are thought to be used at higher temperatures than the conventional TiAl alloys, typically up to 900 degrees C. However, the beta(0) and omega-related phases are usually induced by Nb-segregation in cast alloys. It is important to reveal the transformation mechanisms of the beta(0) and omega-related phases at elevated temperatures for better design of the alloy and optimizing the heat treatment process. In this study, the interconversion mechanism between the ordered omega and beta(0) phases and the decomposition process of the beta(0) phase in the as-cast Ti-45Al-8.5Nb-0.2W-0.2B-0.02Y (at.%) alloy are studied. The omega(0) particles grow up by richening Nb and rejecting W to the surrounding beta(0) matrix. The beta(0) and omega(0) phase are separated after annealing at 900 degrees C, whereas the omega(0) phase dissolves into the beta(0) matrix after annealing at 950 degrees C. The beta(0) and omega(0) phases undergo beta(0) -> gamma and omega(0) (B8(2) structure) -> D8(8)-omega (D8(8) structure) -> gamma transformation respectively during annealing, and the beta(0) -> gamma transformation can be achieved in several ways. The omega(0) particles with a high Nb content act as pinning points at the beta(0)/gamma boundaries during the beta(0) -> gamma transformation. The corresponding mechanisms of the transformations mentioned above are discussed. (C) 2014 Elsevier B.V. All rights reserved.
Authors
I am an author on this paper
Click your name to claim this paper and add it to your profile.
Reviews
Recommended
No Data Available