The clarification of α″ phase precipitate from β phase in Ti-15Mn alloy by mismatch theory

The precipitation and growth of α″ phase from β phase in Ti-15Mn alloy after solid solution process was experimentally investigated. After heat treatment, the Ti-15Mn alloy consisted of α″ and β phases. The α″ and β phases were analyzed by X-ray diffraction, transmission electron microscopy and Fourier transforms. The results show a coherent relationship between α″ phase and β-Ti matrix, which is (2 0 0)α″ // (1 1 0)β and (0 2 0)α″ // (1 1¯ 0)β. Through calculating one-dimensional and two-dimensional mismatch, it comes to a conclusion that the two-dimensional mismatch of α″ phase and β-Ti matrix is 1.73%. It means that the α″ phase can efficiently precipitate from β-Ti matrix. Furthermore, it grows along the resultant vectors direction which determined by one-dimensional mismatch energy.