负热膨胀(Negative thermal expansion，NTE)材料因其具有热缩冷胀的性质，故在调控材料热膨胀系数(Coefficient of thermal expansion，CTE)方面表现出独特的优势，在复合材料和钎焊领域展现出巨大的潜力。目前NTE材料已在航天、生物医学以及电子信息等领域得到了广泛的应用。在制备复合材料时，将NTE材料作为增强相与正热膨胀材料结合，可以有效调节复合材料的热膨胀系数，将其控制在极低或接近零的水平。在金属基复合材料的制备过程中通过添加NTE增强相，以降低金属基复合材料的热膨胀系数，有效地减少了因热膨胀引起的内部应力，从而延长材料的使用寿命。在钎焊领域中，由于异种母材进行钎焊时热膨胀系数差异较大，接头中会产生较大的残余应力，从而严重影响钎焊接头的性能。在复合钎料中引入NTE材料降低其热膨胀系数，进而减小母材与钎缝之间的热失配，从而有效地降低了接头处的残余应力，以达到提高接头力学性能的目的。
Review on Negative Expansion Materials in Composite Materials and Brazing
Negative thermal expansion(NTE)materials show unique advantages in regulating the coefficient of thermal expansion of materials due to their heat-shrinking and cold-expanding nature,which show great potential in the field of composite materials and brazing.The NTE materials are used to regulate the high coefficient of thermal expansion of metal composite filler,which have been widely used in aerospace,biomedicine,sensors,and electronic information.In the field of composite materials,the combination of NTE and positive thermal expansion material can effectively regulate the coefficient of thermal expansion of composite materials,controlling it at a very low or near-zero level.Some researchers have utilized the property of NTE materials to reduce the coefficient of thermal expansion of metal matrix composites,and reduce the failure problem caused by temperature difference.In the field of brazing,due to the large difference in the coefficient of thermal expansion of dissimilar materials,the large residual stresses will be produced in the brazed joints,which seriously affects the performance of the components.The coefficient of thermal expansion of metal composite filler by introducing negative expansion materials,reducing the difference of the coefficient of thermal expansion between the base material and brazing seam.Therefore,the NTE materials effectively reduces the residual stresses of the brazed joints,and achieves the purpose of improving the mechanical properties of the brazed joints.
negative expansion materialsbrazingmetal matrix compositesresidual stresscoefficient of thermal expansion
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