The institute has developed magnesium based biomimetic materials with high damping, high energy absorption and shape memory

    In addition to high specific strength, specific stiffness, excellent thermal conductivity and electromagnetic shielding properties, magnesium's damping performance is significantly better than most engineering metal materials, and even comparable to some common polymer materials, but its strength and heat resistance is significantly higher than polymer materials, so in shock absorption, energy absorption, noise reduction and other aspects of outstanding advantages.The strength, stiffness, plasticity and fracture toughness of magnesium and its alloys are still lower than those of steel and aluminum alloys.As is known to all, the strength and damping performance of metal materials show a contradictory inverted relationship. On the one hand, the strength can be improved through the restriction of dislocation motion; on the other hand, the damping requires the dislocation to be easy to move and get rid of pinning, which leads to the reliance on classical material reinforcement means at the expense of damping performance.How to toughen magnesium and magnesium alloys without significantly increasing the density and reducing the damping property has become a key scientific challenge.

    Compared with artificial materials, the macroscopic mechanical properties of natural biomaterials are usually much better than the simple addition of their basic structural units.Such as shell, skeleton, etc. present three-dimensional interpenetrating structure on the micro level, and each component phase keeps connected and interspersed, thus realizing the complementary advantages of each component phase in performance and function, as well as the synchronous strengthening and toughening of materials.The understanding of nature's magical "structure-performance relationship" provides a unique way of thinking for the design of new materials with excellent comprehensive performance.

    For areas such as aerospace, precision instruments, recently for the performance requirements of material damping, energy absorption, fatigue and fracture of the Chinese Academy of Sciences institute of metal materials laboratory Liu Zenggan, Zhang Zhefeng, titanium alloy research Li Shujun, Mary, and so on with the United States, China academy of engineering physics at the university of California, Berkeley, natural biological material for reference the concept of three-dimensional interpenetrating microstructure, magnesium melting impregnation to add materials made of nickel titanium alloy frame, building into a lightweight, high strength, high damping and high energy absorption of magnesium - nickel titanium biomimetic composite materials.

    Microscopic three-dimensional interpenetrating biomimetic structures not only realize the complementarity and combination of the ni-Ti reinforced phase and magnesium matrix in terms of performance advantages, but also give the material shape memory and self-repair functions.First of all, the interpenetration of the composed phases in the three-dimensional space is conducive to promoting the stress transfer between the two phases, weakening the stress concentration, making the deformation of the two phases more coordinated and giving better play to the strengthening effect of the niti enhanced phase. The strength of the biomimetic composite material is significantly higher than that of the simple superposition based on the mixing law.Secondly, the matrix and reinforced phase in biomimetic composite materials not only rely on the metallurgical combination of interface, but also exist three-dimensional interpenetration mechanical interlock, which effectively avoids the premature failure caused by interface cracking and endowing the material with good damage tolerance.Thirdly, the penetration of component phases in the biomimetic composite in three-dimensional space not only fully retains the damping property of magnesium matrix, but also introduces new damping mechanisms such as micro-yield and micro-crack into the weak interface between the two phases to further improve the damping property.In addition, in a specific temperature range (> 150 ℃), nickel titanium reinforced skeleton of shape memory effect and the coupling effects on the creep behavior of magnesium matrix, and nickel titanium reply stress is far higher than that of matrix creep stress, so that when the deformation damage of biomimetic composite materials by conventional heat treatment to recover its initial shape and intensity, to shape memory it possesses the effect of the self-healing function, and can use reciprocating cycle.

    Through multiple mechanisms, respectively, improving strength and damping properties, a new type of bionic composites broke through the mutual restriction relations between the two, realize the strength of the magnesium alloy, damping and energy absorption efficiency good combination of a variety of performance, comprehensive performance is better than the currently known engineering materials, demand is expected to become the precision instruments, aerospace and other fields of new type damping shock absorption material.