Quantitative analysis of interleaved degree in lamellar microstructure of titanium alloys

To establish the relationship between mechanical properties and microstructural features, it is necessary to comprehensively describe microstructural characterizations. In present study, an efficient and innovative quantitative method of interleaved degree in lamellar microstructure was developed. Firstly, four types of microstructural variables were defined as key factors that confirmed the microstructural features. Lath length (L) and variation coefficient for distribution of lath angle (CV) were measured to obtain dimension information of laths, and number of lath intersecting points per area (N) and uniformity of lath intersecting points (U) were defined to describe the lath distribution and the lath intersection complexity. Then, the microstructural variables were normalized based on multiple attribute decision-making. Finally, the equation of interleaved degree in lamellar microstructure was established based on entropy weight method. Present quantitative method was applied to analyze the interleaved degree of TC17 alloy containing a basketweave microstructure. It was shown that interleaved degree was higher at a deformation temperature of 930 °C, a height reduction of 40% and a strain rate of 0.1 s⁻¹ and decreased with increasing cooling time. Besides, a model that can theoretically calculate fracture toughness based on tensile properties was utilized to prove the prediction ability of interleaved degree.