Single Crystal Superalloy Research Articles

High temperature cyclic CMAS corrosion of TBCs on second generation single crystal superalloy deposited using beam switching EBPVD technology

High temperature cyclic CMAS corrosion of TBCs on second generation single crystal superalloy deposited using beam switching EBPVD technology

Microstructure and dislocation behavior of nickel-based single crystal superalloy DD6 under high-speed rotation and complex stress at 1050 °C

Microstructure and dislocation behavior of nickel-based single crystal superalloy DD6 under high-speed rotation and complex stress at 1050 °C

Study on the salt-corrosion and oxidation role mechanism of Ni-based single crystal superalloy in the long-term hot corrosion environment

Study on the salt-corrosion and oxidation role mechanism of Ni-based single crystal superalloy in the long-term hot corrosion environment

Coupled modeling of rafting behaviour in nickel-based single crystal superalloys

Coupled modeling of rafting behaviour in nickel-based single crystal superalloys

Review on high-energy beam repair of surface damages in Ni-based single crystal superalloys

Review on high-energy beam repair of surface damages in Ni-based single crystal superalloys

Unveiling the oxidation behavior of tantalum in a nickel-based single crystal superalloy through precise microstructural characterizations

Unveiling the oxidation behavior of tantalum in a nickel-based single crystal superalloy through precise microstructural characterizations

Formation of freckles during casting single crystal superalloys through central cooling and heating process

Formation of freckles during casting single crystal superalloys through central cooling and heating process

Dependence of defects competition on tensile behavior in the Co-based single crystal superalloy induced by precipitation size

Dependence of defects competition on tensile behavior in the Co-based single crystal superalloy induced by precipitation size

Insights into the effect of Ta addition on creep properties in a Re-free nickel-based single crystal superalloy

Insights into the effect of Ta addition on creep properties in a Re-free nickel-based single crystal superalloy

Effect of ppm-level La modification on hot corrosion behaviour of single crystal superalloy CMSX-4

Effect of ppm-level La modification on hot corrosion behaviour of single crystal superalloy CMSX-4

The influence of phase angle on the TMF crack initiation behaviour and damage mechanisms of a single-crystal superalloy

The influence of phase angle on the TMF crack initiation behaviour and damage mechanisms of a single-crystal superalloy

Effect of Co doping on hot corrosion behavior of aluminide coating on Mo-rich single-crystal superalloy exposed to Na2SO4+NaVO3 at 750°C and 900°C

Effect of Co doping on hot corrosion behavior of aluminide coating on Mo-rich single-crystal superalloy exposed to Na2SO4+NaVO3 at 750°C and 900°C

Effect of Pt-Al coating on the fatigue behavior of the single-crystal superalloy at different temperatures

Effect of Pt-Al coating on the fatigue behavior of the single-crystal superalloy at different temperatures

Improved Properties of Ceramic Shells by Optimizing the Surface Composition from Lanthanide-Based Composites

The precision casting of nickel-based single-crystal superalloys imposes stringent requirements on the high-temperature stability and chemical inertness of ceramic shell face coats. To address the issue of traditional EC95 shells (95% Al2O3–5% SiO2) being prone to react with the alloy melt at elevated temperatures, thereby inducing casting defects, this study proposes a lanthanide oxide-based ceramic face coat material. Three distinct powders—LaAlO3 (LA), LaAlO3/La2Si2O7 (LAS), and LaAl11O18/La2Si2O7/Al2O3 (LA11S)—are successfully prepared through solid-phase sintering of the La2O3-Al2O3-SiO2 ternary system. Their slurry properties, shell sintering processes, and high-temperature performance are systematically investigated. The results demonstrate that optimal slurry coating effectiveness is achieved when LA powder is processed with a liquid-to-powder ratio of 3:1 and a particle size of 300 mesh. While LA shells show no cracking at 1300 °C, their face coats fail above 1400 °C due to the formation of a La2Si2O7 phase. In contrast, LAS and LA11S shells suppress cracking through the La2Si2O7 and LaAl11O18 phases, respectively, exhibiting exceptionally high-temperature stability at 1400 °C and 1500 °C. All three shells meet the high-temperature strength requirements for CMSX-4 single-crystal alloy casting. Interfacial reaction analysis and Gibbs free energy calculations reveal that Al2O3-forming reactions occur between the novel shells and alloy melt, accompanied by minor dissolution erosion without other chemical side reactions. This work provides a high-performance face coat material solution for investment casting of nickel-based superalloys.

Microstructural Evolution and its Effect on the Mechanical Properties of a Novel Second‐Generation Single Crystal Superalloys After Thermal Exposure

In gas turbines, critical components such as turbine blades operate under prolonged high‐temperature conditions, which often result in the degradation of the microstructure in a nonuniform manner. In the article, the relationship between the microstructural evolution and mechanical properties of a novel second‐generation nickel‐based single‐crystal superalloy subjected to extended thermal exposure at 900 °C is examined. The results demonstrate that, with increasing the duration of thermal exposure, the γ′ phase size increases from 0.35 μm (0 h, edge length) to 0.46 μm (1000 h, thickness), transitioning from a regular cubic shape to a rafting structure. The tensile properties of the alloy first increase and then decrease. The coarsening behavior of the γ′ phase in the tested alloy aligns with the Lifshitz–Slyozov–Wagner theory (LSW), with a coarsening rate constant of 5.51 × 104 nm3 h−1. Additionally, the Kirkendall effect, driven by the uneven diffusion of alloying elements, results in a rise in both the quantity and size of micropores. Microcracks are more likely to start and spread from the pointed corners of micropores. The coarsening of the γ′ phase, combined with the growing presence of large, irregularly shaped micropores, ultimately contributes to the degradation of the alloy's tensile properties.

Study on the abrasive belt grinding removal mechanism and surface roughness prediction of DD6 single crystal superalloy

Study on the abrasive belt grinding removal mechanism and surface roughness prediction of DD6 single crystal superalloy

Transient Liquid Phase Bonding of Cobalt‐Based Single Crystal Superalloys: Study on the Precipitation Behavior of Borides in the Diffusion‐Affected Zone

This study investigates the precipitation behavior of needle‐like borides in the diffusion‐affected zone (DAZ) during transient liquid phase (TLP) bonding of DD688 single‐crystal cobalt‐based superalloy. The effects of matrix orientation and bonding temperature on boride precipitation are systematically analyzed. The results indicate that M2B‐type borides preferentially grow along the [001] direction at a bonding temperature of 1220 °C. Increasing the matrix orientation deviation from 0° to 45° reduces the number of preferentially grown borides and leads to a dense distribution of small borides near the isothermal solidification zone/DAZ interface. Higher bonding temperatures enhance the preferential growth of borides and reduce the density of small borides near the interface. At 1280 °C, significant morphological changes occur in the DAZ borides, including partial liquation of the matrix. These findings provide insights for optimizing TLP bonding and postweld heat treatment processes to improve the microstructure and mechanical properties of brazed joints in cobalt‐based superalloys.

Microstructural Investigation of Stress-Induced Degradation of Gamma and Gamma Prime Phases on the Surface of the Aerofoil of Nickel-Based Single Crystal Superalloy Turbine Blades

Nickel-based single-crystal superalloy turbine blades are typically manufactured via investment casting followed by a well-established heat treatment process, resulting in a uniform microstructure composed of thin γ channels and cubic-shaped γ’. However, the region near the corner of the aerofoil/platform of the blade exhibits a distinct contrast compared to the surrounding area. High-resolution scanning electron microscopy (SEM) reveals significant degradation of the γ and γ’ phases in the dark contrast region. In this area, the γ’ phase no longer maintains its characteristic cubic morphology and appears partially dissolved or even melted. Although the regularity of the γ/γ’ microstructure is disrupted, the region is still composed of irregular-shaped γ and γ’ phases. Based on these microstructural observations, a possible formation mechanism of the abnormal microstructure is discussed. Although the blades are not exposed to conventional creep conditions during casting and heat treatment, residual stress accumulated during casting may be relieved at elevated temperatures during the heat treatment process. The synergistic effect of stress, temperature, and time may contribute to the formation of the observed abnormal microstructure.

Effects of hot isostatic pressing on the micron-scale residual stress of nickel-based single-crystal superalloys

Effects of hot isostatic pressing on the micron-scale residual stress of nickel-based single-crystal superalloys

Microstructure evolution of single-crystal nickel-base superalloy during the rafting process under thermomechanical fatigue

Microstructure evolution of single-crystal nickel-base superalloy during the rafting process under thermomechanical fatigue