MAR-M200 Cast High Temperature Alloy

MAR-M200 铸造高温合金‍

1、 Material Overview

MAR-M200 is a nickel based high-temperature alloy that has been developed since the mid-20th century. With its high temperature strength, oxidation resistance, and corrosion resistance, it has become a key material in fields such as aerospace, industrial gas turbines, and chemical equipment. This alloy can maintain excellent mechanical stability and structural durability in high temperature environments (above 600 ° C), especially suitable for working conditions such as aircraft engine turbine blades and combustion chambers. Its density is 8.43 g/cm ³, combining lightweight and high-strength characteristics. Its melting point range is 1370-1430 ° C, thermal conductivity is 24.3 W/m ·℃ at room temperature, and electrical resistivity is 0.34 Ω· mm ²/m. Its comprehensive performance is superior to traditional stainless steel and similar nickel based alloys.

2、 Chemical composition and microstructure

MAR-M200 uses nickel (Ni) as the matrix, with the largest proportion of residual, and achieves performance optimization through multi-element alloying:

Main strengthening element: Chromium (Cr, 9.0% -10.0%) enhances antioxidant properties; Molybdenum (Mo, 11.5% -13.5%) and tungsten (W, 12.5%) enhance high-temperature strength through solid solution strengthening; Cobalt (Co, 9% -11%) optimizes thermal stability.

Trace added elements: niobium (Nb, 0.75% -1.25%) and titanium (Ti) promote the precipitation of γ 'phase (Ni ∝ Al/Ti), achieving precipitation strengthening; Zirconium (Zr, 0.03% -0.08%) and boron (B, 0.01% -0.02%) refine grain boundaries and suppress crack propagation.

Its microstructure is reinforced with the γ 'phase as the core, with a volume fraction of over 60%, supplemented by uniformly distributed carbide particles, to jointly enhance its creep resistance and fatigue resistance.

3、 Mechanics and Physical Properties

High temperature mechanical properties

Strength indicators: yield strength at room temperature of 945 MPa, tensile strength of 324 MPa; Can maintain a strength retention rate of over 80% at a high temperature of 700 ° C.

Resilience performance: elongation rate of 65%, cross-sectional shrinkage rate of 50%, impact toughness of 11 J, significantly better than traditional cobalt based alloys.

Creep resistance: Under the condition of 760 ° C/248 MPa, the steady-state creep rate is less than 1 × 10 ⁻⁸⁻¹, suitable for long-term high-temperature service environments.

physical properties

Thermal performance: Specific heat capacity of 113 J/kg ·℃, coefficient of thermal expansion of 14.5 × 10 ⁻⁶/℃ (20-1000 ° C), low thermal stress characteristics reduce the risk of thermal fatigue.

Corrosion resistance: In sulfur-containing and salt spray environments, the oxidation rate is less than 0.1 mm/year, and the surface can be coated with MCrAlY or thermal barrier coatings (TBCs) to further enhance the protective ability.

4、 Heat treatment and processing technology

MAR-M200 铸造高温合金‍Heat treatment process

Solid solution treatment: Maintain temperature between 1295-1562 ° C, dissolve primary γ 'phase and carbides, and achieve tissue homogenization.

Time treatment: Temperature control is carried out in stages (such as 870 ° C/4h+760 ° C/16h) to promote the dispersion and precipitation of secondary γ 'phase, and improve strength and heat resistance.

Excellent processing technology

Precision casting: Single crystal blades are prepared using directional solidification technology, eliminating transverse grain boundaries, increasing temperature bearing capacity by 14-20 ° C, and extending thermal fatigue life by 5 times.

Surface treatment: carburizing, nitriding, or vapor deposition (CVD) processes enhance surface hardness (HV ≥ 800), and thermal barrier coatings (such as YSZ) can reduce blade surface temperature by 100-300 ° C.

Complex molding: Investment casting can produce hollow blades with a wall thickness of 0.5 mm, combined with internal film cooling channel design to achieve efficient thermal management.

5、 Application Fields

aerospace

Aircraft engine: used for turbine blades, guide vanes, and combustion chambers, capable of withstanding 1000-1100 ° C gas erosion and supporting fourth generation engine turbine front temperatures of 1850-2000 K.

Spacecraft components: rocket engine nozzle and re-entry vehicle thermal protection structure, single crystal derived models (such as M200RK) have no grain boundary characteristics and can withstand short-term overheating up to 90% of the melting point.

Energy and Industry

Gas turbine: As a first stage moving blade material, combined with GTD-111 alloy to improve power generation efficiency, it supports the thermal efficiency of combined cycle units to exceed 60%.

Chemical equipment: used in high-temperature reactors, distillation towers, and corrosion-resistant pipelines, resistant to strong acid and alkali media erosion, with a service life 3-5 times longer than traditional materials.

Special equipment

In the field of nuclear power, high-temperature gas cooled reactor structural components and potential candidate materials for nuclear fuel cladding have the ability to resist neutron irradiation embrittlement.