| As an important cast alloy, ZL114A is widely used in aeronautic, astronautic and automobile industry. In order to obtain the good properties modification is often introduced in the process of this alloy. However, the process of modification is complex and difficult to control. The desired properties can not be obtained or even be worsened. Some previous studies proved that superheat treatment can made the structure fine and improved the mechanical properties.In this thesis, by using the Different Scanning Calorimetric (DSC), the effects of melt structure on ZL114A alloy solidification microstructure and mechanical properties were studied. The results show the following:1. The DSC results indicate that above the liquidus temperature, the ZL114A alloy melts structure varies with the increase of temperature. Due to dynamics factors, the melt structure transformation can not reverse completely.2. Effects of cooling rate on the microstructure of Z1114A alloy during solidification were investigated. The second dendrite arm spacing of the alloys were decreased and eutectic silicon was refined and dispersed as the cooling rate increased. DSC test results showed that the liquidus temperature and the binary eutectic temperature were decreased and the ternary/quaternary eutectic reactions and Mg2Si phase were depressed as the cooling rate increased. The microhardness of the alloy at the higher cooling rate was raised.3. The cooling rate in TS-T0 has influence on solidification microstructure strongly. The higher cooling rate of TS-T0 is the finer of microstructure.4. By superheating treatment, the ZL114A alloy tensile strength, elongation and the micro hardness increase compared to the raw material, especially its elongation achieved 15.9%, after the superheat treatment at 820℃, which is much more than that of 16 process. Therefore, the superheat treatment is a alternative way to enhance the alloy mechanics properties of ZL114A..
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