In this study, TA15 titanium alloys were successfully prepared using selective laser melting (SLM). The results show that the microstructure of each TA15 specimen is composed of a large number of acicular α’ martensite crystals accompanied by a lot of dislocations and twin structures in the martensite due to non-equilibrium heating and cooling via SLM. After solution treatment and aging treatment, the martensite structure is successfully transformed into a typical duplex structure and an equiaxial structure. When there is an increase in the solution temperature, the size of the equiaxed primary α phase and the elongation of the specimen gradually increases, while the thickness of the layered secondary α phase and the tensile strength of the specimen decreases accordingly. After solution treatment at 1000 °C, the specimens show the best comprehensive mechanical properties, i.e., a high-temperature tensile strength of 715 MPa and a corresponding elongation of 24.5%. Subsequently, an appropriate solution–aging treatment is proposed to improve the high-temperature mechanical properties of SLMed TA15 titanium alloys in aerospace.

We report the epitaxial growth of multiferroic BiFeO₃ (BFO) film on Si(001) substrate by pulsed laser deposition using CeO₂/yttria-stabilized zirconia (YSZ) as buffer layers. The epitaxial relationships of the films were BFO(001)/CeO₂(001)/YSZ(001)/Si(001) for out-of-plane and [110]BFO‖[100]CeO₂‖[100]YSZ‖[100]Si for in-plane, respectively. Capacitance-voltage characteristics of a Pt/BFO/CeO₂/YSZ/p-Si capacitor exhibited clockwise hysteresis loops with a large memory window of 2.5 V at sweeping voltages of ±16 V. Both the high and low capacitance values showed no obvious degradation after 10⁴ s. The improved retention property was attributed to the use of high-k CeO₂/YSZ insulating layers that effectively eliminated the charge trapping in the heterostructure.

The ThMn₁₂-type SmFe₁₂-based rare-earth permanent magnet has attracted widespread attention due to its excellent intrinsic magnetic properties and high-temperature stability. However, the challenge in realizing continuous non-magnetic or weakly magnetic grain boundary phases equilibrated with the SmFe₁₂ main phase hinders the enhancement in extrinsic magnetic properties of the SmFe₁₂-based permanent magnet, especially for the coercivity. In this work, by controlling the cooling rate, the uniform distribution of paramagnetic Fe₂Ti phases at grain boundaries is achieved in the SmFe₁₂-based alloy ribbon, resulting in a high coercivity of 7.95 kOe. This improvement is attributed to the elimination of the impurity phase within the SmFe₁₂ main phase and the magnetic isolation effect of the grain boundary phase composed of paramagnetic Fe₂Ti, which is directly observed by transmission electron microscopy and further confirmed by micromagnetic simulation. Moreover, first-principles calculations show that the V element can dope into Fe₂Ti and facilitate the transition of its paramagnetic state at room temperature. This study provides new insights into constructing weakly magnetic grain boundary phases for SmFe₁₂-based permanent magnets, offering a novel approach to enhance coercivity.

Developing permanent magnets based on full high abundance rare-earth (RE) elements of Ce, La, and Y offers tremendous potential for the balanced utilization of RE resources, but the magnetic properties of these magnets are restricted due to the magnetic dilution caused by the existence of the paramagnetic REFe2 laves phase. Herein, the non-RE element Ge with high efficiency was introduced to enhance the magnetic performance of Ce-, La-, and Y-based RE–Fe–B nanocrystalline alloys, and the highest maximum energy product [(BH)max] of 65.6 kJ/m3 and an enhanced coercivity (Hcj) of 346 kA/m were achieved in the [(Ce0.8La0.2)0.5Y0.5]16Fe77.5B6Ge0.5 alloy. This improvement is attributed to the increased content of the hard magnetic RE2Fe14B phase with refined grain size, which is further confirmed by micromagnetic simulation. First-principles calculations and a microstructure analysis reveal that the laves phase is effectively suppressed by Ge addition due to the formation of the Ce5Ge3 phase with the lowest formation energy. This work clarifies the positive role of Ge in simultaneously enhancing the Hci and (BH)max of nanostructured (Ce,La,Y)–Fe–B alloys.