| The raw material used is casting AM60B-xZn with solution and aging treatment. The content of alloys microscopic structure and mechanical properties were tested by using ICP, XRD, SEM, Vickers and tensile machine.The AM60B magnesium alloy consists of the α-Mg matrix phase, β-Mg17Al12 phase distribute on the grain boundaries and a little amount of AlMn phase in grain. The dendrites in the alloys were refined when the content of Zn increased, and the MgZn phase appeared.The β-Mg17Al12 phase was solved into the base metal after the AM60B-xZn alloy solution treatment. With the Zn increasing, the grain size of AM60B-xZn alloys were 100μm、97μm、9μm、61μm、46μm、59μm separately. When the contents of Zn are 4%, the average grain size is the finest.The UTS, Yield Strength, elongation and hardness of AM60B all increase with the increase of content of Zn, and they all arrive its maximum at 248MPa,123MPa,9.36% and 70.4(HV) separately. The strengthening mechanism of AM60B-xZn alloys include fine-grain strengthening, solution strengthening and second-phase strengthening, in which fine-grain strengthening plays a leading role. The fracture mechanism of AM60B-xZn alloys are transforming into quasi-cleavage fracture including some little parts of ductile fracture from cleavage fracture with the increase of content of Zn.After aging treatment in the 180℃ for the AM60B-xZn magnesium alloys. The hardness of increased with the rise of Zinc content. The hardness achieved the peak value when the time of aging treatment up to 24h. After aging treatment, for the same Zinc content, it can be a regular pattern of the hardness along with the increasing of aging time. On the basis of Brinell hardness results, when the Zinc content is 4%, the hardness of alloy reached the maximum. After aging treatment to AM60B-(3-5)Zn, the precipitated β-Mg17Al12 and MgZn compounds mainly distributed in grain boundary. The precipitation strengthening is the main reinforcing mechanisms of AM60B-xZn alloy. |
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