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The current design strategies focus on the solidification characteristics to discover new MACs with promising properties in an enormous search space composed of considerable composition combinations in a specific system. In the present study, the associated correlations between alloying elements and solidification interval characteristics are uncovered via machine learning (ML) in the multi-component systems. Given the Fe–Cr–Ni–Al system, testing accuracy value using FNN model in identifying the input and output features is above 89%, and the Cr and Al are the critical elements. With these understanding, FeCrNiAl 0.8 alloy was successfully designed and prepared, and the properties are tested to confirm the reliability of the alloy design strategies. The experimental investigations not only provide strong evidence for the predicted accuracy, but also find superior mechanical properties. The designed FeCrNiAl 0.8 alloy exhibits fracture strength and plastic strain of 2839 MPa and 41%, respectively, accompanied with remarkable work hardening capacity. Beyond that, the extraordinary specific strength make it competitive against virtually known high performance metals and polycrystalline superalloys even in high temperature applications. Our work provides new ideas to search for compositionally complex alloys and is also applicable to assist in developing advanced MACs for engineering applications.

Effect of aging temperature on modulated structures of Co-free 00Ni 12 Cr 5 Mo 3 TiAlV maraging steel was studied. With increasing the aging temperature, the modulated structures become more obvious. When the temperature is lower, the occurrence of spinodal decomposition only can be indicated by a little elongation of diffraction spots. However, when the temperature is higher, the in situ intermetallic precipitates of modulated structures are distributed along 0 1 0 direction (the elastic soft direction). The coherent relationship was kept between matrix and precipitates. The extra high strength and good ductility are mainly attributed to the in situ precipitation strengthening and coherent effect of modulated structures.

To improve the oxidation resistance of Mo Si fused slurry coating fabricated in vacuum, Mo Si N multi-layer coatings were synthesized on C/C composites in nitrogen atmosphere by fused slurry using same Mo and Si element powders. The phase compositions and microstructures were characterized by X-ray diffractometry (XRD), optical microscopy (OM), scanning electron microscopy (SEM) with energy-dispersive spectroscopy (EDS). The results indicate that the Mo Si N coating contains SiC inner layer and MoSi2/Si main layer, which was similar with Mo Si coating. Additionally, a thin outer layer with nano-filiform morphology has been found on the coating surface, which consists of SiC, Si3N4, AlN, Al2O3 and sialon phase. Oxidation experiments show that the Mo Si N multi-layer coating exhibits excellent oxidation resistance at 1400 °C and anti-oxidizing potential ability at 1450 °C.

The precipitation microstructure and the associated hardness and electrical conductivity have been systematically studied in a 7150 alloy during the ageing treatment. The evolution of the GP zones during the one step and the two step ageing processes is discussed in details. Experimental results show that the electrical conductivity of the alloy treated in the two step ageing regime is higher than that of the alloy treated in the one step ageing regime. The two step ageing regime increases the stability of GP I zones and restrains the coarsening of precipitates. During the two step ageing treatment, GP I zones are present when the ageing temperature at the second stage is 160 °C (36 h), which could not be detected in the one step ageing for short times at the same temperature. Both the GP I and GP II zones disappeared after ageing for 4 h at 180 °C. The achievement of the high strength of the alloy is ensured by a large volume fraction of fine GP zones and η′ precipitates.