Aluminium-chromium Master Alloy，Aluminium chromium Alloy，AlCr Alloy，E FORU

**Product Datasheet: Aluminium-Chromium Master Alloy (Al-Cr Alloy)** **Version:** 1.0 | **Date:** 2025-04-02 --- ### **1. General Overview** Aluminium-Chromium Master Alloy (Al-Cr Alloy) is a specialized grain-refining and strengthening additive used to introduce chromium into aluminium alloy systems. Chromium forms intermetallic compounds that enhance corrosion resistance, control grain structure, and improve elevated temperature properties. This master alloy is particularly valuable for applications requiring enhanced stress corrosion resistance and microstructural stability. --- ### **2. International Standards** Al-Cr master alloys are specified in several international standards: - **ISO:** ISO 209-1 (Wrought aluminium and aluminium alloys) - **ASTM:** ASTM B179 (Standard Specification for Aluminum Alloys in Ingot and Molten Forms) - **EN:** EN 1676 (Aluminium and aluminium alloys — Master alloys) - **GB/T:** GB/T 27677 (Aluminium-chromium master alloy) - **Typical Master Alloy Grades:** Al-5%Cr, Al-10%Cr, Al-15%Cr --- ### **3. Chemical Composition (Weight %)** Typical composition ranges for Al-Cr master alloy: | Element | Content (%) | Role & Remarks | |------------------|-------------------|------------------------------------------| | Chromium (Cr) | 2.0 – 15.0 | Primary alloying element | | Iron (Fe) | ≤ 0.25 | Impurity control | | Silicon (Si) | ≤ 0.20 | Impurity control | | Copper (Cu) | ≤ 0.05 | Impurity control | | Zinc (Zn) | ≤ 0.05 | Impurity control | | Other Impurities | ≤ 0.15 total | — | | Aluminium (Al) | Balance | Base metal | --- ### **4. Physical Properties** | Property | Value / Range | |---------------------------|-----------------------------------| | Density | 2.7 – 3.0 g/cm³ (varies with Cr content) | | Melting Range | 660 – 850°C | | Intermetallic Phases | Al₇Cr, Al₄₅Cr₇, Al₁₁Cr₂ | | Hardness (Brinell) | 45 – 80 HB (master alloy form) | | Thermal Conductivity | 120 – 180 W/m·K | | Electrical Conductivity | 40 – 55 % IACS | --- ### **5. Key Characteristics & Advantages** - **Corrosion Resistance:** Significantly improves stress corrosion cracking resistance - **Grain Refinement:** Controls grain growth during heat treatment - **Elevated Temperature Stability:** Maintains strength at moderately high temperatures - **Recrystallization Inhibition:** Suppresses recrystallization in wrought alloys - **Anodizing Quality:** Improves surface finishing characteristics --- ### **6. Product Applications** - **Aerospace Alloys:** 7xxx series alloys for structural components - **Marine Applications:** Shipbuilding components exposed to seawater - **Automotive:** Heat-resistant engine components, pistons - **Architectural:** Extrusions for building facades and structures - **Electrical:** Heat sink materials with good corrosion resistance - **Pressure Vessels:** Components requiring stress corrosion resistance --- ### **7. Available Forms** - **Master Alloy:** Ingots, notch bars, granules - **Standard Sizes:** 5–15 kg ingots - **Special Forms:** Custom-sized pieces for automated feeding systems --- ### **8. Technical Guidelines for Use** - **Addition Rate:** 0.1–0.5% Cr to the melt (depending on base alloy) - **Melt Temperature:** 720–780°C - **Holding Time:** 30–60 minutes for complete dissolution - **Stirring:** Requires thorough mechanical stirring - **Cooling Rate:** Moderate to prevent excessive segregation --- ### **9. Metallurgical Effects** - Forms fine dispersoids of Al₇Cr and other intermetallic phases - Provides dispersion strengthening through coherent precipitates - Controls recrystallization by forming grain boundary pinning particles - Enhances quench sensitivity in heat-treatable alloys - Improves fracture toughness in high-strength alloys --- ### **10. Performance in Different Alloy Systems** | Base Alloy | Cr Addition Effect | Typical Applications | |------------|-------------------|---------------------| | **7xxx (Al-Zn-Mg)** | Improves stress corrosion resistance | Aircraft structures | | **6xxx (Al-Mg-Si)** | Controls grain growth | Architectural extrusions | | **5xxx (Al-Mg)** | Enhances corrosion resistance | Marine applications | | **4xxx (Al-Si)** | Modifies silicon particles | Automotive castings | --- ### **11. Quality Control Parameters** - Chromium content consistency (±0.1%) - Intermetallic particle size distribution - Microstructural homogeneity - Chemical composition certification - Dissolution rate verification --- ### **12. Health, Safety & Handling** - Use standard personal protective equipment (gloves, safety glasses) - Avoid inhalation of fine particles during processing - Store in dry conditions to prevent surface oxidation - Follow standard industrial hygiene practices - Chromium in this form is less hazardous than hexavalent chromium compounds --- ### **13. Comparison with Other Transition Metals** | Element | Grain Refinement | Corrosion Resistance | Cost | Applications | |---------|------------------|---------------------|------|--------------| | **Chromium** | Good | Excellent | Medium | Aerospace, Marine | | **Manganese** | Very Good | Good | Low | General Purpose | | **Zirconium** | Excellent | Good | High | High-Temperature Alloys | | **Titanium** | Excellent | Fair | Medium | General Foundry | --- ### **Disclaimer** This information is provided for technical reference only. Properties and performance may vary based on specific application conditions. Users are advised to conduct trials to determine suitability for their processes. The manufacturer is not liable for misuse or application failures. Always follow good foundry practices and safety guidelines.

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 2287 gallon liquid totes Special package is available on request.