Aluminium-strontium. Master Alloy，Aluminium strontium Alloy，AlSr Alloy，E FORU

**Product Datasheet: Aluminium-Strontium Master Alloy (Al-Sr Alloy)** **Version:** 1.0 | **Date:** 2025-04-02 --- ### **1. General Overview** Aluminium-Strontium Master Alloy (Al-Sr Alloy) is a highly specialized and widely used modification alloy designed for superior eutectic silicon modification in aluminium-silicon casting alloys. Strontium effectively transforms the acicular (needle-like) eutectic silicon structure into a fine fibrous morphology, dramatically improving mechanical properties, particularly ductility and impact strength. This master alloy has become the industry standard for high-quality aluminium casting applications where reliability and performance are critical. --- ### **2. International Standards** Al-Sr master alloys are governed by several international standards: - **ASTM:** ASTM B179 (Standard Specification for Aluminum Alloys in Ingot and Molten Forms) - **ISO:** ISO 209-1 (Wrought aluminium and aluminium alloys) - **EN:** EN 1676 (Aluminium and aluminium alloys - Master alloys) - **GB/T:** GB/T 8734 (Aluminium alloy master alloys) - **JIS:** JIS H 2118 (Aluminium alloy master alloys) - **Typical Master Alloy Grades:** Al-5%Sr, Al-10%Sr, Al-15%Sr, Al-20%Sr --- ### **3. Chemical Composition (Weight %)** Typical composition ranges for Al-Sr master alloy: | Element | Content (%) | Role & Remarks | |---------------------|-------------------|------------------------------------------| | Strontium (Sr) | 3.0 – 20.0 | Primary modification element | | Calcium (Ca) | ≤ 0.05 | Critical impurity control | | Barium (Ba) | ≤ 0.02 | Impurity control | | Sodium (Na) | ≤ 0.01 | Impurity control | | Iron (Fe) | ≤ 0.25 | Impurity control | | Silicon (Si) | ≤ 0.20 | Impurity control | | Other Impurities | ≤ 0.10 total | — | | Aluminium (Al) | Balance | Base metal | --- ### **4. Physical Properties** | Property | Value / Range | |---------------------------|-----------------------------------| | Density | 2.8 – 3.2 g/cm³ | | Melting Range | 660 – 1050°C (Sr melts at 777°C) | | Intermetallic Phases | Al₄Sr, Al₂Sr, AlSr | | Thermal Conductivity | 100 – 140 W/m·K | | Electrical Conductivity | 30 – 45 % IACS | | Vickers Hardness | 70 – 130 HV | | Coefficient of Thermal Expansion | 21–24 × 10⁻⁶/K | --- ### **5. Key Characteristics & Advantages** - **Superior Modification:** Transforms eutectic silicon from acicular to fine fibrous structure - **Excellent Ductility:** Increases elongation by 100–300% in modified alloys - **Long Modification Life:** Effective for extended periods (8–12 hours) - **Low Gas Pickup:** Minimal hydrogen absorption compared to sodium modifiers - **Consistent Results:** Highly reproducible modification performance - **Improved Castability:** Enhanced fluidity and reduced hot tearing tendency --- ### **6. Product Applications** - **Automotive Castings:** Engine blocks, cylinder heads, transmission cases - **Aerospace Components:** Structural castings, brackets, housings - **Pressure-Tight Castings:** Pump housings, valve bodies, hydraulic components - **Architectural Castings:** High-quality decorative and structural elements - **Consumer Products:** Premium cookware, machinery components - **Electrical Enclosures:** Motor housings, transformer cases - **Military Equipment:** High-reliability structural components --- ### **7. Available Forms** - **Master Alloy:** Ingots, notch bars, waffle plates - **Special Forms:** Rods, cones for precise feeding - **Standard Sizes:** 5–15 kg ingots - **Waffle Plates:** Designed for controlled dissolution rates --- ### **8. Technical Guidelines for Use** - **Addition Rate:** 0.1–0.3% master alloy to achieve 0.01–0.03% effective Sr - **Melt Temperature:** 720–760°C - **Holding Time:** 30–60 minutes for complete modification - **Stirring:** Gentle mechanical stirring recommended - **Treatment Window:** Effective modification lasts 6–10 hours - **Over-modification Control:** Avoid exceeding 0.03% Sr content --- ### **9. Modification Performance Comparison** | Modification Element | Modification Efficiency | Duration | Gas Pickup | Cost Effectiveness | |---------------------|------------------------|----------|------------|-------------------| | **Strontium (Sr)** | Excellent | Long | Low | High | | **Sodium (Na)** | Excellent | Short | High | Medium | | **Antimony (Sb)** | Good | Permanent | Low | Medium | | **Calcium (Ca)** | Fair | Medium | Medium | High | --- ### **10. Mechanical Property Enhancement** | Property | Unmodified Alloy | Sr-Modified Alloy | Improvement | |----------|------------------|-------------------|-------------| | **Tensile Strength (MPa)** | 180–220 | 200–250 | 10–15% | | **Elongation (%)** | 2–4 | 8–15 | 200–300% | | **Impact Strength (J)** | 4–8 | 12–20 | 150–200% | | **Quality Index** | 200–250 | 300–380 | 40–50% | --- ### **11. Quality Control Parameters** - Strontium content consistency (±0.15%) - Critical impurity control (Ca, Ba, Na < 0.05%) - Modification efficiency testing - Microstructural evaluation - Chemical composition certification --- ### **12. Health, Safety & Handling** - **Pyrophoric Nature:** Fine particles may ignite spontaneously in air - **Moisture Sensitivity:** Reacts with moisture to produce hydrogen gas - **Personal Protection:** Wear gloves, safety glasses, and flame-resistant clothing - **Ventilation:** Adequate fume extraction during addition - **Fire Safety:** Class D fire extinguisher required in processing areas - **Storage:** Sealed containers in dry, well-ventilated areas --- ### **13. Microstructural Effects** - **Silicon Morphology:** Transforms from acicular to fine fibrous structure - **Eutectic Colony Size:** Reduces eutectic colony size significantly - **Intermetallic Formation:** Forms Al₄Sr compounds - **Phase Distribution:** Creates homogeneous silicon particle distribution --- ### **14. Economic Benefits** - **Process Efficiency:** Reduced scrap rates and improved yield - **Quality Premium:** Superior mechanical properties command higher prices - **Energy Savings:** Lower pouring temperatures possible - **Recycling Value:** Maintains modification in recycled alloys --- ### **15. Research & Development Trends** - **Optimized Addition Methods:** Development of more efficient feeding systems - **Multi-element Systems:** Combined Sr-P and Sr-Ti-B systems - **Additive Manufacturing:** Modification of Al-Si powders for 3D printing - **Environmental Solutions:** Development of greener modification technologies - **Process Monitoring:** Real-time modification efficiency control --- ### **Disclaimer** This information is provided for technical reference only. Properties and performance may vary based on specific application conditions, processing parameters, and base alloy composition. Strontium modification requires careful control to avoid over-modification and gas pickup. Due to the pyrophoric nature of strontium, strict safety protocols must be followed during handling and storage. Users are advised to conduct thorough testing to determine optimal addition rates for their specific applications. Always consult with materials engineering specialists for critical applications in automotive and aerospace industries.

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 2314 gallon liquid totes Special package is available on request.