Zhang Jiachen

Northwestern Polytechnical University | NWPU · Shaanxi Key Laboratory of Space Materials Science and Technology

Molybdenum (Mo) addition was investigated for its influence on the interfacial characteristics of γ′-phase strengthened Co-based superalloys with γ/γ′ dual phases. Advanced characterization techniques, including scanning transmission electron microscopy (STEM), atom probe tomography (APT), and high-resolution X-ray diffraction (HR-XRD), were employ...

Molybdenum (Mo) addition was investigated for its influence on the interfacial characteristics of γ′-phase strengthened Co-based superalloys with γ/γ′ dual phases. Advanced characterization techniques, including scanning transmission electron microscopy (STEM), atom probe tomography (APT), and high-resolution X-ray diffraction (HR-XRD), were employ...

This study explores the effects of Re and Ta interactions on TCP (topologically close-packed) phase precipitation in experimental alloys under long-term thermal exposure. TCP phase is thoroughly examined and analyzed in terms of its location, morphology evolution, structural identification, and phase transition, employing thermo-dynamic calculation...

The distribution of the dendrite arrays and the primary dendrite arm spacing (PDAS) in large-sized single-crystal superalloy blade was investigated by Voronoi tessellation. The dendrite arrays were hexagonal at the airfoil center and random at the trailing edge. The PDAS was gradually increased from the leading edge (about 370 μm) to the trailing e...

The distributions of tungsten (W) in Ni-based single crystal superalloys with different Re and Ta contents are characterized and specified by atom probe tomography. The results show that Ta changes the partitioning behavior of W and rejects it from the γ′-precipitate to the γ-matrix, while Re shows the opposite effect, which is consistent with the...

Due to the excellent high-temperature mechanical performance, nickel-based single-crystal superalloys have developed indispensable mate-rials in the preparation of advanced aero-engines. The high rate solidification (HRS) method is a Bridgman directional solidification technology, which moves the mold filled with molten metal out of the heating zon...

In response to the increased demand for very long-term service reliability of industrial gas turbine (IGT) blades, the microstructure stability of two single crystal (SX) superalloys with different Re addition (0Re and 2Re in wt.%, named as alloy 0Re5Ta and 2Re5Ta) were investigated during long-term thermal exposure (>5000 h) at 900°C, with the hel...

Through a combination of atom probe tomography (APT) and theoretical calculations, the distributions of tungsten (W) at the γ/γ′ interfaces with exposure effects in a Ni-based single crystal superalloy are investigated. W shows the reversal partitioning behavior during long-term thermal exposure, partitioning from γ-matrix to γ′-precipitates, accom...

The distribution of Re in a Ni-based single crystal superalloy is specified by atom probe tomography after different heat treatment. At higher temperatures (950-1100°C), the Re diffusivity in γ matrix is becoming smaller than the actual effective diffusion for γ΄ growth, during the subsequent cooling process and the interface migration, consequentl...

At present, inlet temperature of advanced industrial gas turbines can reach more 1500°C, hot corrosion resistant superalloys with higher temperature capacity are required. Ni-based single crystal superalloys have become the key materials for industrial gas turbines. Excellent comprehensive high-temperate properties, resistance for corrosion and oxi...

In this study, the microstructural evolution and microstructure-property relationship of a Re-containing single crystal superalloy after long-term thermal exposure for up to 20,000 h at 900 °C have been investigated. The results showed that the microstructure of the experimental alloy significantly degraded after thermal exposure, including the coa...

A novel efficient method to design eutectic medium-entropy alloys with typical lamellar structure is successfully proposed. The CrCoNiNb0.48 alloy is prepared with microstructure comprised of FCC and Laves phases. After laser remelting, the nano-scale eutectic lamellar is formed and the eutectic lamellar spacing is refined to approximately 30 nm fr...

Alloy design of Cr-Co-Ni-Ta eutectic medium entropy alloys (EMEAs) was performed through a CALPHAD method coupled with experimental study, with the aim to attain high phase stability as well as excellent mechanical properties. Based on calculated pseudo-binary diagram, CrCoNiTax (x = 0.1, 0.3, 0.4, 0.5, 0.7) medium entropy alloys were investigated....

The microstructural evolution in Re-containing Ni-based single crystal superalloys with different Tantalum (Ta) content (2Ta, 5Ta and 8Ta in wt %) was investigated. Ta addition significantly affected the γ′ precipitate morphology, γ/γ′ lattice misfit and microstructural stability during long-term aging. Results showed that the partitioning behavior...

The effect of 2 wt.% Re addition on the microstructure stability and γ/γ′ interfacial characteristics of designed Ni-based single crystal (Ni-SX) superalloys during long-term aging up to 2000h under 900°C and 1000°C was investigated. Re addition significantly affected the γ′ precipitate morphology, γ/γ′ lattice misfit and microstructural stability...

The peritectic reaction L + β-NiAl → γ′ during directional solidification in a Ru-containing nickel-based single crystal superalloy was investigated by the planar interface solidification and the phase transformation process was clarified in detail. The phase transformation mechanism of the peritectic reaction was further studied in the combination...

The solidification characteristics and as-cast microstructures of a Ru-containing nickel-based single crystal superalloy were systematically investigated through thermal analysis, Thermo-Calc simulation, the planar interface solidification experiment, and the directional solidification quenching experiment. The main solidification transition temper...

The morphological evolution and coarsening kinetics of γ′ precipitates in a Re-containing Ni-based single crystal superalloy were investigated during isothermal aging at 900, 950 and 1000 °C. After heat treatment, well-defined cuboidal γ′ precipitates with low misfit was obtained within the experimental alloy. Then coarsening rate constants and pa...