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The MCrAlY(M=Ni, Co or NiCo)has become a widely used bond-coat material of thermal barrier coatings (TBCs) due to its advantages of high-temperature oxidation resistance and high thermal expansion coefficient, with the continuous increase in turbine inlet temperature of aero engines and gas turbines. However, the stress distribution at the interface between the bond and top coating in thermal barrier coatings becomes more complicated under a high-temperature service environment. The failure of the bond-coat leads to the spalling of the top coating, which limits the development of the thermal protection coating field. The development process of the bond-coat was briefly described.The failure behavior of the bond-coat interface due to high-temperature phase transition, increased thermal and growth stresses, and S-element diffusion was focused on, and the failure mechanism of the bond-coat interface was analyzed. The research on improving the bond-coat interface failure at home and abroad was summarized. The synergistic strengthening of MCrAlY by rare earth and nanoparticles is proposed, which provides a research direction for the future optimization design of thermal bond-coat systems.

The 6061-T651 aluminum alloy was strengthened by torsional deformation with the torsion angles of 90°, 180° and 360°. The quasi-static and dynamic compressive properties of the samples before and after torsional deformation were investigated. The results show that the grain size of the samples remains unchanged at first with the increase of the torsion angle, and then begins to decrease. However, the Kernel average misorientation(KAM) value continues to increase with the increase of the torsion angle. The quasi-static and dynamic compression experiments show a slight increase in the yield strength of the samples with the increase of the torsion angle. For the same torsion angle, the dynamic yield strength is significantly higher than the yield strength at quasi-static loading. The strain rate experiment shows that the yield strength of the sample increases with the increase of strain rate, but compared with the untorsional sample, the strain rate sensitivity of the 360° torsional sample is significantly reduced. Based on the experimental data, the parameters in the Cowper-Symonds constitutive model were fitted. The stress-strain curves obtained from this model are in good agreement with the experimental results.

The 6061 aluminium alloy is a heat treatable reinforced aluminium alloy containing magnesium and silicon as its main alloying elements. It is commonly used in the aerospace and automotive industries due to its excellent mass to strength ratio and high thermal conductivity, but is particularly susceptible to the formation of coarse columnar crystals and thermal tearing, particularly during SLM processing.TiH2/AA6061 aluminium-based composite powders were prepared by the low-energy ball milling assembly modification method, and the titanium-containing 6061 aluminum alloy specimens were prepared by selective laser melting technique.The microstructure and mechanical properties of the samples with different TiH2 contents were systematically investigates. The results show that the addition of 1% TiH2 (mass fraction, the same below) results in the formation of a continuous equiaxed crystal zone at the alloy melt pool boundary, the average grain size decreases from 59.8 μm to 2.53 μm, and the coarse columnar grains and cracks inhibit, and with the addition of 1.5% TiH2, the coarse columnar grains of the SLM specimens inhibit completely and only a few small columnar grains exist. The microstructure transformation is attributed to the enhancement of the constituent undercooling by Ti elements and the in-situ reaction to form L12-Al3Ti nucleation particles, which form a coherent interface with the Al matrix and have a strong heterogeneous nucleation effect, thus significantly promoting the transformation from columnar to equiaxed crystals and grain refinement of the Al matrix. After selective laser melting, the tensile strength of 6061 aluminum alloy with 1% TiH2 addition is 274 MPa, the yield strength is 238 MPa, and the elongation after break is 18%.

Based on the "octahedral structure model" of three-dimensional reticulated porous materials, the mathematical deductions are introduced one by one for the mathematical relations of their basic physical and mechanical properties in this paper. The present review on these deductions covers the unidirectional tension and the multidirectional tension/compression of porous materials, as well as the conductivity and the fatigue property. Emphasis is placed on describing the equivalent circuit of the inner structure of porous materials, and the force action model both of quasi-rigid body and deformed body structure of porous materials under unidirectional tension. On this basis, the compressive strength is discussed, and the biaxial tension and triaxial tension/compression are mathematically deducted and analyzed. According to this octahedron model, the mathematical relations of mechanical properties can be also obtained from the deduction of unidirectional tension and compression, for porous materials under loading of non-direct tension and compression.

The "octahedral structure model" is introduced for three-dimensional reticulated porous materials, as well as the mathematical relations of their basic physical and mechanical properties. On this basis, the verification works about some performance relations, including the conductivity and tension, etc, are reviewed in this paper. A number of issues were discussed with the emphases on the practicality of these mathematical and physical relations, the rationality of the correction coefficients, the significant influence on the calculation results, and the allowable stress and the plastic index value of the corresponding dense body were also analyzed in details. According to this mathematical and physical relationship, the performance indexes such as the electrical resistivity of porous products can be calculated by the easily measurable basic parameters like the porosity. The experimental results prove this way feasible. Therefore, this method can be superior to the finite element and other complex computational methods.

Three-dimensional reticulated porous materials are excellent engineering materials, and their application cover energy engineering, bioengineering, aerospace, environmental protection, transportation, etc. Author of this paper put forward a simplified structure model of octahedron based on the structural characteristics of these materials. On this basis, serial mathematical relations were obtained for their performance. This model and the related mathematical characterization of the basic physical and mechanical properties of this kind of materials,from unidirectional tension to multidirectional tension and compression,as well as conductivity and specific surface area were comprehensively introduced. The origin and characteristics of the simplified structural model were described comprehensively, and compared with other similar models; different property models and their relationships were explained one by one. Among them, the representative problems including the thin beams assumption of pore struts, the bending of pore struts and the restraint force of bearing units for the loaded porous body, and the correction coefficient and the plastic index value involved in the tension or/and compression relationship. The theoretical results were verified by the experiment of samples prepared in production line, which were well practicable.

Honeycomb sandwich plates are used widely in the aerospace industry. Building accurate finite element models of honeycomb sandwich plates is necessary for analyzing and optimizing the microvibration that occurs in spacecraft. A finite element dynamic model of a honeycomb plate was built, and then by using orthogonal design of experimental computation, the most important material parameters of honeycomb core equivalent model were identified. Through the global optimization based on adaptive sampling guided by response surface model, the parameters of honeycomb core were updated efficiently. The average error of first six modal frequencies of the updated finite element model against experimental result is reduced to less than 1%.