Development of alpha-phase morphologies during low temperature isothermal heat treatment of a Ti-5Al-5Mo-5V-3Cr alloy

作者：Dehghan Manshadi Ali^*; Dippenaar Rian J

来源：Materials Science and Engineering A-Structural Materials Properties Microstructure and Processing, 2011, 528(3): 1833-1839.

DOI：10.1016/j.msea.2010.09.061

• Ti-5553 alloy
• omega-Assisted nucleation
• alpha morphology
• XRD

Development of different morphologies of the alpha-phase and their influence on the mechanical properties during low temperature isothermal aging of the near-beta titanium alloy Ti-5Al-5Mo-5V-3Cr (Ti-5553) have been studied. A wide variety of different morphologies of the alpha-phase resulted from variations of the isothermal temperature and/or time. While after aging at 673 K or higher, a Widmanstatten star-shape was the dominant morphology of the alpha-phase, aging at lower temperatures resulted in the formation of triangular-shaped precipitate morphology. The first alpha-phase nucleated after 10 min isothermal holding time at 673 K, and the volume fraction increased to more than 80% after 8 h of holding time. This increase in the volume fraction of the alpha-phase caused an increase in the micro-hardness of the bulk material. X-ray diffraction and microstructural analyses provided evidence of omega-assisted nucleation of the alpha-phase. It is proposed that this mechanism by which the alpha-phase nucleates on pre-existing omega-phase particles account for the formation of the very large number of small alpha-particles that precipitated in the beta-matrix.

• 出版日期2011-1-25