Effect of Heat Treatment on Microstructure Evolution and Mechanical Properties of 2.5 vol% TiBw/TA15 Composites with Different Deformation Statuses

Abstract

In this study, heat treatments of solution and aging are performed on 2.5 vol% TiBw/TA15 composites with different deformation statuses. The results indicate that the mechanical properties of the 2.5 vol% TiBw/TA15 composites are influenced by the microstructure, which is affected by the thermal processing and heat treatment history. The elongated α phase is obtained in the powder extrusion process followed by air cooling (EAC) and is then spheroidized in the rotary swaging process. After solution at 970 °C, the α phase is further spheroidized and partially transformed into the β phase at different degrees depending on the deformation status. After aging at 930 °C, the volume fraction of the equiaxial α phase increases significantly and the transformed β phase is decomposed into the clustered α + β laths at different degrees. Although experiencing the same post‐heat treatment, the influence of the deformation history affects the microstructure. After solution at 970 °C for 30 min and aging at 930 °C for 100 min, the EAC + RSAC sample exhibits an ultimate tensile strength of 1335 MPa and an elongation of 4.2%. Additionally, the fracture mechanism consists of the brittle fracture of the TiB whiskers and the ductile failure of the TA15 matrix.

Tensile Deformation Behavior and Dynamic Recrystallization of TA15 Alloy over a Wide Temperature Range

“…TA15 is a typical near-α titanium alloy that contains a large amount of Al (an α-phase stabilizing element) and small amounts of Mo and V (β-phase stabilizing elements). Therefore, it has the advantages of both αand α þ β-type titanium alloys, [1,2] including low density, excellent hightemperature properties, good plastic formability, weldability, and fatigue resistance. [3][4][5][6] Owing to its long operating life at 500 °C, it is used for manufacturing high-temperature loadbearing components, such as aircraft bulkheads, airframes, long trusses, and engine compressor disks, [7][8][9] and is one of the most important high-temperature structural materials in the aerospace field.…”