Fig. 4.

Phase transformation kinetics of the Ti-2wt.% La alloy. Formation of α starts in the L₁ + β field and, subsequently, α transforms from β during cooling. a Color-coded 2D plot of the evolution of {hkl} reflections of β, α, La-bcc and La-fcc for a representative 2θ range of 2.25–4.55°, combined with the simultaneous evolution of volume fractions of crystalline phases obtained from Rietveld analysis during continuous cooling from 950 °C down to 400 °C with 20 °C min⁻¹. No changes are observed for T < 400 °C. b Color-coded 2D plot of the evolution of {002}α Bragg reflections for an azimuthal angle (ψ) range 0–180° during continuous cooling between 950–850 °C with 20 °C min⁻¹. c Presence of α coexisting with β and L₁ phases during transformation is revealed in the complete Debye-Scherrer rings acquired at 905 °C and 875 °C. d Nucleation of α particles (pointed by arrows) at former β/L₁ interfaces is visible in a microstructure quenched from 950 °C. Scale bar, 5 μm (right side); 2 μm in magnified image (left side). e Normalized pole figures of {110}β and {002}α reconstructed from a gauge volume of 1 × 1 × 5 mm³, indicating that α does not inherit the texture of the parent β phase right after β → α transformation of Ti-2La during cooling down to 850 °C. The transformation of α from β (β → α) is reflected in the rapid increase in the volume fraction of α between 900–850 °C shown in a