The improvement of the creep properties of single-crystal superalloys is always strongly motivated by the vast growing demand from the aviation, aerospace, and gas engine. In this study, a static magnetic-field-assisted solidification process significantly improves the creep life of single-crystal superalloys. The mechanism originates from an increase in the composition homogeneity on the multiscales, which further decreases the lattice misfit of γ/γ′ phases and affects the phase precipitation. The phase-precipitation change is reflected as the decrease in the γ′ size and the contents of carbides and γ/γ′ eutectic, which can be further verified by the variation of the cracks number and raft thickness near the fracture surface. The variation of element partition decreases the dislocation quantity within the γ/γ′ phases of the samples during the crept deformation. Though the magnetic field in the study destroys the single-crystal integrity, it does not offset the benefits from the compositional homogeneity. The proposed means shows a great potential application in industry owing to its easy implement. The uncovered mechanism provides a guideline for controlling microstructures and mechanical properties of alloys with multiple components and multiple phases using a magnetic field.

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Cr-25Nb alloy was prepared by mechanical alloying (MA) and hot pressing (HP), and the influences of milling time on the density and oxidation property of samples were investigated. During the studying of the effect of different ball grinding time on oxidation resistance, we discover that the relative density of the Cr-25Nb alloy would increase with the ball grinding time increasing, but when it was oxidized at 1200°C for 5 h in the air, the gain weight rate of the oxidized samples does not only decreased with the ball milling time increasing. In the period of MA 0 to 20 h, the gain weight rate of the oxidized samples reduced with the ball milling time increasing. When the ball milling time further increased, the gain weight rate increased and the oxidation resistance of samples went down. Thus, the oxidation resistance of sample of MA 20 is best. The oxide layer appearance of MA 15 h, MA 20 h, MA 35 h were observed by SEM, respectively. It is found that the oxide layer thickness of specimen of MA 20 hour is thinnest. From the result of EDS and XRD, Cr 2 O 3 was formed on the outer oxide layer. However, the oxides in the inner layer were mainly Cr 2 O 3 and CrNbO 4 .

The change of the mushy‐zone length of a nickel‐based single‐crystal superalloy during the static‐magnetic‐field‐assisted directional solidification was investigated. The results show that the longitudinal static magnetic field can influence the mushy‐zone length. For the magnetic field less than 1.0T, the mushy‐zone length decreases with increasing the magnetic field intensity. Nevertheless, when the magnetic field is greater than 1.0T, the mushy‐zone length begins to increase. The phenomenon is attributed to the competitive relationship between the temperature gradient in the mushy‐zone and the solidification‐temperature range in controlling the mushy‐zone length. Under the low and high intensity of the magnetic field, the temperature gradient and the solidification‐temperature range play the main roles in controlling the mushy‐zone length, respectively.