| Due to the characteristics of high specific strength,easy forming,high damping,and low cost,magnesium alloys have important applications in aerospace,automotive,aircraft and other fields.However,lower strength and poor plasticity are the main bottlenecks restricting the wide application of magnesium alloys.In this paper,starting from magnesium-based solid solution,rapid solidification spray banding and spark plasma low-temperature sintering process are used to study in detail the multi-phase precipitation evolution and mechanical properties of magnesium-based supersaturated solid solution bulk alloys containing Gd and Zn.Taking Mg96.9Gd2.7Zn0.4 alloy as the research object,from master alloy smelting,rapid solidification thin strip preparation,spark plasma sintering and other processes,comprehensive use of X-ray diffraction(XRD),scanning electron microscopy(SEM),transmission electron microscopy(TEM)and other research methods to analyze the structure of samples in various states,.Microstructure analysis,by comparing the changes in mechanical properties and microstructure differences of the samples before and after different process parameters,summarized the best process of the alloy.First of all,the research results of the rapid solidification thin strip process show that the best preparation process parameters of the single-roll copper shaft spinning method:the round-hole quartz tube after BN spray treatment,the vacuum degree of the cavity is 0.05MPa(argon atmosphere)),the melting current is 30A,the injection pressure is 20kPa,and the copper roll speed is about 90-95 rpm.The Mg96.9Gd2.7Zn0.4 thin strip with a length of up to 3000mm,a thickness of about 50?m and a width of about 3mm was successfully prepared..The influence of the process parameters of spark plasma sintering rapid solidification ribbons such as sintering temperature(430?450?470?),sintering time(3?5?10min)and sintering pressure(40?45?50MPa)on the microstructure evolution and mechanical properties of the alloy block is mainly analyzed.law.The research results show that the sintering temperature also has a significant effect on the structure of the solid solution.The strength of the main peaks(002)and(101)does not change much,but the relative strength of the crystal planes(102)(110)and(013)increases with the increase of temperature.The main reason may be related to the precipitation of Mg3Gd and the long-period stacking ordered phase(Long-Period Stacking Ordered Phase);at the same time,the sintering temperature has a significant effect on the precipitation and growth of the Mg3Gd phase.As the temperature increases,the maximum size of the particles decreases from less than 1?m increased to 1.4?m;the sintering pressure mainly affects the density of the sample.Under 40MPa,the relative density is between 97-99%,and under 45-50MPa,both are greater than 99%;the sintering time has an effect on the microstructure of the sintered block.The growth of grains in the structure and the segregation of elements have an important effect.High temperature and long time can significantly promote the growth of Mg3Gd and LPSO phases,and the grain size also increases slightly,but not significantly.Under the best process parameter conditions Bottom:sintering temperature 450?,sintering pressure 45MPa,sintering time 5min.The yield strength,compressive strength and fracture strain of the sintered alloy are 305MPa,475MPa and 0.12,respectively. |
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