The mechanism of compression-induced variant selection in 0001-textured titanium alloys: A combined experimental and molecular dynamics simulation study

K Ma and P Wang and SM Jiang and HY Sun and X Ma, JOURNAL OF ALLOYS AND COMPOUNDS, 1020, 179121 (2025).

DOI: 10.1016/j.jallcom.2025.179121

The microstructural evolution of 0001-rich textured titanium alloy under hot compression and subsequent cooling is investigated, with the variant selection mechanism elucidated through a combined approach of experimental analysis and molecular dynamicssimulations. During the BCC -> HCP phase transformation upon cooling, the pattern has been established between precipitated martensitic alpha' phase variants and their micro- structural properties, such as lattice spacing, stress and orientation. For the 0001-textured Ti-6Al-4V alloy subjected to hot compression and cooling, EBSD results show the preferred 0001 texture is 45 degrees away from compression direction, while the preferred 1120 texture aligns approximately 0 degrees, 45 degrees or 90 degrees from compression direction. A series of schematic transformation processes are presented to explain the deformation behavior of alpha-Ti simulated under high-strain conditions with compression along various crystal directions of 0001, 1120 and 1010 respectively. During cooling, variant selection mechanism consistently favors the HCP variant with smallest (001)beta ->(1120)alpha contraction and highest Schmid factor for 0001(1120) slip. Notable twinning formations, such as 1011, 1012, 1013 twins, are observed and identified by their misorientation angles around 60 degrees, and 90 degrees respectively. Shockley partial dislocations are observed at location of HCP stacking faults while dense 1/3<100> Hirth dislocations are extending along basal planes in parallel with grain boundary between adjacent HCP grain. The findings of this work underscore the significant influence of mechanical loading on alpha-Ti, potentially offering an innovative approach to tailor microstructure through controlled thermomechanical processing.

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