Rene 95 Nickel Based Superalloy,E FORU

### **René 95 Nickel-Based Superalloy** #### **Overview** **René 95** is a high-strength, **powder metallurgy (P/M)** nickel-based superalloy developed for critical high-temperature rotating components in gas turbine engines. It was one of the first superalloys to be commercially produced primarily via the P/M route, which was necessary to achieve its very high volume fraction of strengthening phases without the severe segregation inherent in conventional casting. The alloy is designed to deliver an exceptional combination of **ultimate tensile strength** and **creep resistance** at temperatures up to approximately 650°C (1200°F). Its high strength is derived from a complex microstructure containing a high density of fine gamma prime (γ') precipitates, achieved through a controlled heat treatment process. René 95 is typically processed via **Hot Isostatic Pressing (HIP)** and often followed by isothermal forging, and is used in the **"directly aged"** condition to maximize strength. --- #### **Chemical Composition (Weight % - Typical)** The composition of René 95 is highly optimized for strength, with significant additions of gamma prime formers. | Element | Content (%) | | :--- | :--- | | **Nickel (Ni)** | **Balance** | | **Cobalt (Co)** | **8.0** | | **Chromium (Cr)** | **14.0** | | **Molybdenum (Mo)** | **3.5** | | **Tungsten (W)** | **3.5** | | **Aluminum (Al)** | **3.5** | | **Niobium (Nb)** | **3.5** | | **Titanium (Ti)** | **2.5** | | **Carbon (C)** | **0.05 - 0.15** | | **Boron (B)** | **0.01** | | **Zirconium (Zr)** | **0.05** | * **Aluminum, Niobium, Titanium:** The primary formers of the strengthening **gamma prime (γ')** phase (Ni₃(Al, Ti, Nb)). The combined content results in a very high volume fraction of γ', which is the key to its high strength. * **Cobalt:** Increases the γ' solvus temperature and provides solid solution strengthening. * **Chromium:** Provides oxidation and hot corrosion resistance. * **Molybdenum & Tungsten:** Potent solid solution strengtheners in the gamma matrix. * **Carbon, Boron, Zirconium:** These elements segregate to grain boundaries, forming carbides and borides that improve grain boundary strength and ductility, enhancing creep and stress-rupture life. --- #### **Physical & Mechanical Properties** The following table outlines the key properties of René 95 in its typical HIP + heat-treated condition. | Property | Value / Description | | :--- | :--- | | **Density** | ~8.3 g/cm³ | | **Melting Range** | ~1330 - 1360 °C (2425 - 2480 °F) | | **Gamma Prime (γ') Solvus** | ~1160 °C (2120 °F) | | **Thermal Conductivity** | Low, typical of nickel-based superalloys (~11.5 W/m·K at 100°C) | | **Mean Coefficient of Thermal Expansion** | ~12.9 μm/m·°C (20-1000°C) | | **Tensile Strength (RT)** | **Extremely High,** ~1650 MPa (240 ksi) | | **Yield Strength (0.2% Offset, RT)** | **Extremely High,** ~1350 MPa (195 ksi) | | **Elongation (RT)** | ~10 - 16% | | **Creep Rupture Strength** | **Excellent.** Capable of sustaining very high stresses at temperatures up to **650°C (1200°F)**. | --- #### **Key Characteristics & Applications** **Key Characteristics:** 1. **Ultra-High Strength:** René 95 possesses one of the highest strength levels among polycrystalline nickel-based superalloys, which is its defining characteristic. 2. **Powder Metallurgy Processing:** The P/HIP (Powder/Hot Isostatic Pressing) process is essential to achieve a chemically homogeneous and fine-grained microstructure free of gross segregation, enabling its high alloy content. 3. **Direct Aging:** It is typically used in a "directly aged" condition after HIP or forging, which involves a high-temperature solution treatment followed by a multi-step aging process to precipitate a fine and dense distribution of γ' particles. 4. **Good Balance of Properties:** While optimized for strength, it maintains sufficient ductility, fracture toughness, and creep resistance for its intended applications. **Typical Applications:** René 95 is exclusively used for the most critically stressed rotating components in gas turbine engines, where failure is not an option: * **High-Pressure Turbine Disks (HPT Discs/Rotors):** Its primary application. These disks operate under tremendous centrifugal stress at elevated temperatures. * **Compressor Disks (Rear Stages):** Used in the high-pressure, high-temperature stages of the compressor. * **Turbine Spools and Hubs:** Other high-integrity rotating parts in the engine's hot section. * **Integrally Bladed Rotors (IBRs or Blisks):** Where the disk and blades are manufactured as a single component from this high-strength material. --- #### **International Standards** As a proprietary, high-performance aerospace alloy, René 95 is governed by stringent proprietary material specifications from engine manufacturers (e.g., GE, Rolls-Royce). However, it is covered by key aerospace material specifications that define its chemical and processing requirements. | Standard Type | Designation | Description | | :--- | :--- | :--- | | **Aerospace Material Specification (AMS)** | **AMS 7852** | This is the primary governing standard for "Superalloy Powder, Nickel Base, 62Ni - 14Cr - 8Co - 3.5Mo - 3.5Nb - 3.5W - 2.5Ti - 3.5Al, Vacuum Atomized," which is the powder precursor for René 95. | | **Aerospace Material Specification (AMS)** | **-** | The consolidated product (forgings, HIP billets) is typically controlled by more specific process-oriented specifications from OEMs, often referencing AMS 7852 for the powder quality. | | **Manufacturer Specifications** | **Various (OEM-specific)** | The definitive processing, heat treatment, and final property requirements are detailed in proprietary OEM specifications. These are critical for ensuring the material meets the rigorous performance and safety standards for flight. | --- #### **Summary** In summary, **René 95** is a landmark ultra-high-strength nickel-based superalloy whose commercialization was enabled by powder metallurgy technology. Its exceptionally high strength, derived from a high volume fraction of gamma prime precipitates in a fine, homogeneous microstructure, makes it ideally suited for critical rotating components like turbine disks. While newer alloys have since been developed, René 95 remains a benchmark for high-strength P/M superalloys and has been extensively used in military and commercial aircraft engines, representing a significant achievement in materials science for aerospace propulsion.

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 3200 gallon liquid totes Special package is available on request.