The microstructure and properties of TiB2/7056 composites with pre-stretching treatments prior to aging heat treatment were investigated by scanning electron microscopy,and transmission electron microscope combined with room temperature mechanical,Charpy impact and stress corrosion methods.The results show that the dislocation density of TiB2/7056 composites increases significantly when the degree of pre-stretching before aging increases,the diameter of the intragranular precipitated phase after aging heat treatment increases,and the morphology of the precipitated phase at the grain boundaries transformes from a chain-like shape to a coarse discontinuous shape,with no precipitation precipitation band broadening.The strength of TiB2/7056 composite first increases and then decreases while the impact toughness and elongation decrease.Especially,the stress corrosion resistance of TiB2/7056 composite is significantly improved after pre-stretching(the propagation rate decreases by one order of magnitude).The reason is that precipitating the discontinuous coarse grain boundary inhibites the expansion of stress corrosion crack.
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