TC11 Titanium Alloy
TC11 is a widely used α+β titanium alloy (composed of both α and β phases) known for its excellent combination of high-temperature strength, creep resistance, and processability. It is particularly valued in aerospace and aviation industries, especially for components operating under elevated temperatures. Below is a detailed breakdown:
1. Basic Information
Alloy Type: α+β titanium alloy (dual-phase structure, with adjustable phase ratio via heat treatment).
Core Characteristics:
High-temperature stability (long-term service temperature up to 500°C).
Excellent creep resistance (resistant to deformation under sustained high-temperature loads).
Good strength-toughness balance at both room and elevated temperatures.
Suitable for forging and welding, enabling the production of complex structural parts.
2. Chemical Composition (mass fraction, %)
TC11’s composition is tailored to enhance high-temperature performance and mechanical properties:
Element Content Range Function
Titanium (Ti) Balance Matrix element
Aluminum (Al) 6.0 – 7.0% Strengthens α phase, improves heat resistance and strength
Molybdenum (Mo) 3.5 – 4.5% Stabilizes β phase, enhances high-temperature strength and creep resistance
Zirconium (Zr) 1.5 – 2.5% Improves high-temperature stability and refines grains
Tin (Sn) 0.5 – 1.0% Strengthens α phase, enhances creep resistance at high temperatures
Silicon (Si) 0.15 – 0.35% Promotes precipitation strengthening, further improving creep resistance
Iron (Fe) ≤0.30% Controlled impurity (excess reduces toughness)
3. Key Properties
(1) Mechanical Properties (typical values, after heat treatment)
Tensile Strength (room temperature): 950 – 1100 MPa.
Yield Strength (room temperature): 850 – 950 MPa.
Elongation: 10 – 15% (good plasticity for forming).
Impact Toughness: ≥30 J/cm² (adequate fracture resistance).
Hardness (HRC): 32 – 38.
(2) High-Temperature Performance
Service Temperature: Long-term stable service at 450 – 500°C (superior to many α+β alloys like TC4, which is limited to ~300°C).
Creep Resistance: Excellent creep strength at 500°C (e.g., creep rate <1×10⁻⁷ h⁻¹ under 300 MPa load for 1000 hours). (3) Other Properties Density: ~4.5 g/cm³ (lightweight advantage over steel). Corrosion Resistance: Good in atmospheric, marine, and most chemical environments (similar to other titanium alloys). Weldability: Moderate to good weldability (TIG or electron beam welding); welded joints retain ~85 - 90% of base metal strength with proper heat treatment. 4. Heat Treatment TC11’s properties are significantly adjustable via heat treatment, with common processes: Solution Treatment + Aging: Solution: Heat to 900 - 950°C (above β-transus temperature, ~990°C, to partially dissolve β phase), hold 1 - 2 hours, then water quench. Aging: Heat to 500 - 600°C, hold 4 - 8 hours, air cool. This process maximizes strength and high-temperature stability by precipitating fine α phase in the β matrix. Annealing: Heat to 700 - 800°C, hold 2 - 4 hours, air cool. Improves machinability and reduces internal stress (used for intermediate processing steps). 5. Processability Forging: Excellent hot forgeability at 950 - 1100°C (above β-transus for uniform grain structure), suitable for manufacturing large forgings like turbine disks. Machining: Moderate machinability; requires sharp tools and coolant to avoid high temperatures (which can cause work hardening or oxidation). Forming: Good hot formability (e.g., rolling, bending) at 800 - 900°C; cold forming is possible but may require annealing for complex shapes. 6. Applications TC11 is primarily used in high-temperature structural components, especially in: Aero-Engines: Turbine disks, compressor blades, and casings (operating at 400 - 500°C). Aerospace: Aircraft engine mounts, high-temperature ducts, and structural parts requiring strength at elevated temperatures. Industrial Machinery: High-temperature valves, pressure vessels, and tools for petrochemical or power generation industries. 7. Comparison with Similar Alloys Property TC11 TC4 (Ti-6Al-4V) TA15 (Near-α) Tensile Strength 950-1100 MPa 900-1100 MPa 850-950 MPa Service Temp 500°C 300°C 500°C Creep Resistance Excellent Moderate Good Forgability Excellent Good Good Note: TC11 outperforms TC4 in high-temperature strength and creep resistance, while offering better forging properties than near-α alloys like TA15, making it ideal for hot-end aero-engine components. Summary TC11 is a high-performance α+β titanium alloy celebrated for its superior high-temperature strength, creep resistance, and processability. Its ability to maintain stability at 500°C, combined with good forging and welding properties, makes it a key material in aerospace and aero-engine manufacturing, particularly for components subjected to sustained elevated temperatures.