720 Nickel Superalloy,MASS7252, MSRR 7252. EMS 73105,E FORU

### **Product Introduction: Alloy 720 (Li) Nickel-Based Superalloy (MASS7252, MSRR7252, EMS73105)** **Alloy 720** is a high-strength, precipitation-hardenable nickel-based superalloy specifically developed for critical rotating components in gas turbine engines. It is renowned for its exceptional combination of high tensile strength, superior fatigue resistance, and excellent creep rupture life at temperatures up to 1300°F (705°C) and beyond. The "Li" variant denotes a version with a carefully controlled, lower carbon content which optimizes ductility and impact strength without significantly compromising strength. To achieve its maximum potential, Alloy 720 is typically processed via **Powder Metallurgy (PM)** and subsequent isothermal forging or Hot Isostatic Pressing (HIP). This advanced manufacturing route ensures a uniform, fine-grained microstructure that is essential for the high reliability and performance required in aerospace applications. The specifications **MASS7252**, **MSRR7252**, and **EMS73105** are proprietary standards, primarily from Rolls-Royce, governing its production and quality. --- #### **1. Chemical Composition (Weight %)** The chemical composition of Alloy 720Li is tightly controlled to achieve an optimal balance of strength and damage tolerance. | Element | Content (%) | Element | Content (%) | | :--- | :--- | :--- | :--- | | **Nickel (Ni)** | Balance | **Tungsten (W)** | 1.00 - 1.50 | | **Chromium (Cr)** | 15.70 - 16.30 | **Molybdenum (Mo)** | 2.75 - 3.25 | | **Cobalt (Co)** | 14.50 - 15.70 | **Carbon (C)** | 0.010 - 0.025 (Low) | | **Titanium (Ti)** | 4.75 - 5.25 | **Boron (B)** | 0.010 - 0.020 | | **Aluminum (Al)** | 2.25 - 2.75 | **Zirconium (Zr)** | 0.025 - 0.055 | | **Iron (Fe)** | ≤ 0.25 | **Silicon (Si)** | ≤ 0.10 | | **Manganese (Mn)**| ≤ 0.10 | **Sulfur (S)** | ≤ 0.005 | **Key Microstructure:** The alloy's high strength is derived from a high volume fraction (approximately 40-45%) of the ordered gamma prime (γ') phase, Ni₃(Al, Ti). The precise balance of Al and Ti is critical for forming this strengthening phase. The low carbon content ("Li") minimizes the formation of brittle grain boundary carbides, improving ductility and fatigue crack growth resistance. --- #### **2. Physical Properties** Typical physical properties for Alloy 720Li are provided below. | Property | Metric Units | Imperial Units | | :--- | :--- | :--- | | **Density** | 8.07 g/cm³ | 0.292 lb/in³ | | **Melting Range** | ~1330 - 1380 °C | ~2425 - 2515 °F | | **Thermal Conductivity (20°C)** | 11.2 W/m·K | 77.7 Btu·in/hr·ft²·°F | | **Mean Coefficient of Thermal Expansion (20-1000°C)** | 15.1 μm/m·°C | 8.4 μin/in·°F | | **Modulus of Elasticity (Tensile)** | 218 GPa | 31.6 x 10⁶ psi | --- #### **3. Mechanical Properties (Typical for Heat-Treated Condition)** Mechanical properties are developed through a solution and double aging heat treatment, optimized for the PM processed material. **Common Heat Treatment:** * **Solution Treat:** ~1160°C (2120°F), oil or fan cool. * **Aging:** Double step aging at ~760°C (1400°F) and ~650°C (1200°F). **Typical Mechanical Properties (At Room Temperature):** | Property | Value (Typical) | | :--- | :--- | | **Tensile Strength** | 1590 MPa (230 ksi) | | **Yield Strength (0.2% Offset)** | 1170 MPa (170 ksi) | | **Elongation** | 18% | | **Reduction of Area** | 20% | **Typical Elevated Temperature Properties (At 650°C / 1200°F):** | Property | Value (Typical) | | :--- | :--- | | **0.2% Yield Strength** | 1035 MPa (150 ksi) | | **Stress Rupture Life (650°C / 690 MPa)** | 90+ hours | --- #### **4. International Standards & Specifications** Alloy 720 is predominantly governed by proprietary specifications from original equipment manufacturers (OEMs), with Rolls-Royce being a primary user. **Primary Specifications:** * **MASS7252 / MSRR7252:** These are Rolls-Royce material and process specifications. MASS7252 typically covers the material requirement for the powder, while MSRR7252 covers the processed component (e.g., forged from powder). * **EMS 73105:** This is another Rolls-Royce engineering material specification that defines the requirements for Alloy 720Li components, including chemistry, mechanical properties, and non-destructive testing. **Other/Related Standards:** * **AMS:** While not as common, it may be produced under guidelines for premium-quality PM superalloys. * **UNS:** UNS N07720 is sometimes used as a general identifier. --- #### **5. Product Applications** Alloy 720Li's primary application is in the high-stress compressor and turbine sections of advanced gas turbine engines. * **Aerospace & Gas Turbines:** * **High-Pressure Compressor Discs (Blisks)** * **Turbine Discs and Rotors** * Shafts * Compressor blades and vanes (for later stages) * **Industrial Gas Turbines (IGT):** * Rotors and discs for high-performance land-based turbines. --- #### **Summary of Key Advantages** * **Exceptional High-Strength:** Offers an outstanding balance of very high tensile and yield strength, along with superior fatigue and creep resistance. * **Optimized Damage Tolerance:** The "Li" (Low Carbon) chemistry provides improved ductility, impact strength, and fatigue crack growth resistance compared to the standard version, which is critical for rotating components. * **Superior Microstructural Consistency:** The Powder Metallurgy + Forging route ensures a homogeneous, fine-grained structure free from segregation, leading to highly reliable and predictable performance. * **Proven in Critical Service:** A well-established material for the most demanding rotating parts in modern aero-engines, enabling higher operational temperatures and efficiencies. **Disclaimer:** The information provided here is for reference purposes. Alloy 720Li is a highly specialized PM superalloy where properties and performance are critically dependent on the precise powder production, consolidation, forging, and heat treatment processes mandated by the governing specifications (MASS7252, MSRR7252, EMS73105). For all applications, strict compliance with the official OEM specifications and the processor's data sheets is mandatory.

Packing of Standard Packing: Typical bulk packaging includes palletized plastic 5 gallon/25 kg. pails, fiber and steel drums to 1 ton super sacks in full container (FCL) or truck load (T/L) quantities. Research and sample quantities and hygroscopic, oxidizing or other air sensitive materials may be packaged under argon or vacuum. Solutions are packaged in polypropylene, plastic or glass jars up to palletized 3136 gallon liquid totes Special package is available on request.