Aluminum-Chromium Master Alloy, AlCr, 7429-90-5, 7440-47-3

ALUMINUM-CHROMIUM (AlCr) MASTER ALLOY T

Product Name: AlCr (Aluminum-Chromium Master Alloy)
Alloy System: Al-Cr binary alloy system
Primary Use: Hardness-enhancing additive for aluminum alloys, corrosion resistance improvement, high-temperature strength development

SECTION 1: PRODUCT IDENTIFICATION AND CHEMICAL IDENTITY

PRODUCT DESCRIPTION AND EXPLANATION:

Aluminum-Chromium (AlCr) master alloy is a pre-alloy (master alloy) containing controlled amounts of chromium within an aluminum matrix. Master alloys are concentrated alloys used to add specific elements to aluminum alloys in a controlled and homogeneous manner.

AlCr master alloy is used to add the element chromium to aluminum-based alloys. Chromium is added to aluminum alloys to increase hardness and wear resistance, improve corrosion resistance, and provide high-temperature strength. Chromium forms intermetallic phases with aluminum (such as CrAl₇, CrAl₄) that contribute to dispersion strengthening and maintain mechanical properties at elevated temperatures.

In aluminum alloys, chromium is particularly effective in improving corrosion resistance in aggressive environments. Chromium also provides grain refinement in Al-Si casting alloys, improving mechanical properties. AlCr master alloys are essential components in aerospace, automotive, and industrial equipment applications requiring high performance.

This master alloy is supplied in rod, ingot, or granule form and can be produced with chromium contents ranging from 1% to 30% according to customer requirements. AlCr master alloy provides a reliable and homogeneous source for adding chromium to the final alloy in aluminum foundries and alloy manufacturing facilities.

SECTION 2: CHEMICAL COMPOSITION

CHEMICAL COMPOSITION EXPLANATION:

The chemical composition of AlCr master alloy is designed to contain controlled amounts of chromium ranging from 1% to 30% within an aluminum matrix. The chromium content can be customized according to customer requirements and final application needs. As chromium percentage increases, the alloy's hardness, wear resistance, and corrosion resistance increase, but a slight decrease in ductility may be observed. Impurity levels are strictly controlled to ensure alloy quality. CAS numbers for Aluminum (7429-90-5) and Chromium (7440-47-3) are provided for chemical identification and regulatory compliance.

SECTION 3: PHYSICAL PROPERTIES

PHYSICAL PROPERTIES EXPLANATION:

AlCr master alloy is supplied in rod, ingot, or granule form. It has a silver-gray color with a characteristic metallic appearance. Density varies significantly depending on chromium content; while pure aluminum has a density of ~2.70 g/cm³, pure chromium has a density of ~7.19 g/cm³. As chromium content increases, the alloy's density increases from 2.7 to 7.2 g/cm³.

The melting point ranges from 600-650°C depending on the exact alloy composition. Chromium addition affects the melting point of aluminum (~660°C). Electrical conductivity decreases significantly with chromium addition; therefore, AlCr master alloys are not used in applications requiring high conductivity. Thermal conductivity is at a low-medium level. Al-Cr alloys are generally non-magnetic.

SECTION 4: FUNCTIONAL PROPERTIES

FUNCTIONAL PROPERTIES EXPLANATION:

The most important functional property of AlCr master alloy is its ability to significantly increase the hardness and wear resistance of aluminum alloys. Chromium forms intermetallic phases (such as CrAl₇, CrAl₄) with aluminum that contribute to dispersion strengthening, improving hardness, wear resistance, and high-temperature strength.

Chromium also improves corrosion resistance, especially in aggressive environments. It enhances the stability of the aluminum oxide layer, providing better passivation. In Al-Si casting alloys, chromium provides grain refinement that improves mechanical properties. Chromium addition also improves oxidation resistance at elevated temperatures.

AlCr master alloy provides precise alloy control; chromium content can be precisely adjusted to optimize the final alloy's hardness, corrosion resistance, and high-temperature properties.

SECTION 5: TYPICAL APPLICATIONS

APPLICATION AREAS EXPLANATION:

Hardness and Wear Resistance: AlCr master alloy is used in machinery parts, gears, wear-resistant components, and industrial equipment. Chromium significantly increases alloy hardness and wear resistance.

Corrosion Resistance Development: Chromium improves corrosion resistance in chemical processing equipment, marine applications, and aggressive environments.

High-Temperature Strength: AlCr alloys are used in aerospace structural parts, engine components, and exhaust systems requiring high-temperature strength.

Al-Si Casting Alloys: In Al-Si casting alloys, chromium provides grain refinement that improves mechanical properties and casting quality.

SECTION 6: STORAGE AND TRANSPORT

STORAGE AND TRANSPORT EXPLANATION:

AlCr master alloy should be stored in a dry and cool environment, protected from moisture and direct sunlight. Due to chromium content, appropriate protection measures should be taken to prevent surface oxidation during long-term storage. Under proper storage conditions, shelf life is unlimited. Packaging varies depending on product form: rod and ingot forms are shipped on wooden pallets or in metal crates, while granule form is shipped in closed containers (drums or bags). During transport, care should be taken to prevent the product from contacting moisture and to protect it from mechanical damage.

SECTION 7: SAFETY INFORMATION

SAFETY PRECAUTIONS:

• Inhalation: Avoid inhalation of dust. Ensure adequate ventilation during melting operations.

• Skin Contact: Not hazardous under normal use; however, dust form may cause skin irritation.

• Eye Contact: In case of dust contact, rinse with plenty of water.

• Melting: Chromium fumes may form during melting operations. Use local exhaust ventilation or fume hood.

• Toxicity: Chromium compounds (such as chromates, Cr⁶⁺) can be toxic and carcinogenic. Elemental chromium (Cr⁰) and alloy form are less toxic, but caution should be exercised during melting and processing where chromium compounds may form.

• PPE Recommendations: Wear protective gloves (heat-resistant), safety goggles (for dust and splashes), and dust mask or respiratory protection if necessary.

• Dust Explosion: Aluminum dust can be explosive; avoid dust formation during processing.

SECTION 8: MECHANICAL PROPERTIES (EFFECT IN FINAL ALLOY)

The typical mechanical properties of Al-Cr alloys obtained by adding AlCr master alloy to the final alloy are given below. These values vary depending on chromium content, other alloy components, and processing conditions.

MECHANICAL PROPERTIES EXPLANATION:

When AlCr master alloy is added to the final alloy, chromium content significantly affects mechanical properties. Chromium increases hardness and wear resistance through the formation of fine intermetallic particles (CrAl₇, CrAl₄) that provide dispersion strengthening. However, ductility (elongation) decreases as chromium content increases.

Important advantages of AlCr alloys include high-temperature strength retention and improved corrosion resistance. Chromium enhances passivation by increasing the stability of the aluminum oxide layer. Mechanical properties vary significantly depending on the exact alloy composition, processing conditions, and heat treatment.

SECTION 9: SUMMARY AND CRITICAL NOTES

SUMMARY:

Aluminum-Chromium (AlCr) master alloy is a pre-alloy containing controlled amounts of chromium (1-30%) within an aluminum matrix. It is supplied in rod, ingot, or granule form. Density ranges from 2.7-7.2 g/cm³ depending on chromium content, and melting point ranges from 600-650°C.

AlCr master alloy is used to add chromium to aluminum alloys. Chromium significantly increases hardness and wear resistance, improves corrosion resistance, and provides high-temperature strength. It is particularly valuable in aggressive environments and high-temperature applications. It also provides grain refinement in Al-Si casting alloys.

Store in dry and cool environment, protected from moisture and direct sunlight. Not hazardous under normal use; however, avoid inhalation of dust and ensure adequate ventilation during melting operations. Chromium compounds may be toxic; handle with care. Personal protective equipment (gloves, safety goggles, dust mask) is recommended.

Basic Properties:

Main Application Areas:

Key Safety Points:

• NOT HAZARDOUS: Not hazardous under normal use

• DUST RISK: Avoid inhalation of dust

• TOXICITY: Chromium compounds may be toxic; handle with care

• MELTING RISK: Chromium fumes may form during melting; ensure adequate ventilation

• PPE: Gloves, safety goggles, dust mask should be used

• STORAGE: Store in dry, cool environment away from direct sunlight

CRITICAL NOTES:

1. Hardness and Wear Resistance Increase: AlCr master alloy significantly increases the hardness and wear resistance of aluminum alloys through the formation of fine intermetallic particles (CrAl₇, CrAl₄) that provide dispersion strengthening. This makes AlCr alloys ideal for wear-resistant applications.

2. Corrosion Resistance Development: Chromium enhances passivation by increasing the stability of the aluminum oxide layer. This makes AlCr alloys suitable for aggressive environments and marine applications.

3. High-Temperature Strength: Chromium addition provides retention of mechanical properties at elevated temperatures. This is a critical advantage for components operating in high-temperature conditions in aerospace and automotive industries.

4. Grain Refinement in Al-Si Casting Alloys: In Al-Si casting alloys, chromium provides grain refinement that improves mechanical properties and casting quality.

5. Adjustable Chromium Content: AlCr master alloy can be produced with chromium contents ranging from 1% to 30% according to customer requirements. As chromium percentage increases, hardness and corrosion resistance increase, but a decrease in ductility may be observed.

6. Chromium Toxicity Warning: Although elemental chromium (Cr⁰) and alloy form are less toxic, chromium compounds (such as chromates, Cr⁶⁺) can be toxic and carcinogenic. Consideration should be given to the formation of chromium compounds during melting and high-temperature operations. Adequate ventilation and respiratory protection should be provided. This should also be considered in waste management.

7. Aluminum Dust Safety: Aluminum dust generated during processing of AlCr alloy can be explosive. Avoid dust formation during processing and take appropriate dust control measures.

IMPORTANT DISCLAIMER: This Technical Data Sheet (TDS) is for informational purposes only and is prepared based on available technical data. The information provided is believed to be accurate. However, the user is solely responsible for determining the product's suitability for their specific applications and for complying with all applicable local, national, and international regulations and safety requirements. For complete safety, storage, handling, transport, waste, and regulatory compliance information, please refer to the official Safety Data Sheet (SDS/MSDS) provided by the manufacturer/supplier. Users are obligated to test the product in their own processes and applications. All occupational health and safety rules must be observed when working with AlCr master alloy.