| The relationship of preparation conditon and microstructures of as-cast in situZr-Based composites with ductile crystalline precipitates were studied, as well as theprocess of dentrites changing to spheroidal crystal microstructures of as-cast in situZr-Based bulk metallic glass (BMG) composites with ductile crystalline precipitates werestudied in this dissertation. We study the evolution rule and mechanism of themicrostructures in situ Zr-Based composites by the formation of the microstructures, thethermodynamics and the kinetics,and we lodge the deformation mechanism of ball crystal.The essential research work for the dissertation were in three aspects:(1)Zr56.2Ti13.8Nb5.0Cu6.9Ni5.6Be12.5as-cast in situ composites with ductile crystallineprecipitates with different diameters were prepared, and the result can tell us that the ballaverage diameter and the volume fractions of spheroidalβphase of as-cast in situ Zr-Basedbulk metallic glass composites with ductile crystalline precipitates were increased camelong with the diameter increasing.(2) Zr60Ti14.67Nb5.33Cu5.56Ni4.44Be10was choosed for thisreseach. We changed the parameter in this experiment and got a series clubbed samplesas-cast in situ Zr-Based composites with ductile crystalline precipitates with different heatpreservation times. We saw the the process of dentrites changing to spheroidal crystalgradually and this process told us that the heat preservation times can affectβphasepattern as well as phase dimensional size as-cast in situ Zr-Based composites with ductilecrystalline precipitates,and enough heat preservation time is the guarantee for theβphasecomplete spheroidization.(3)As the evolution rule for the basis, the essential of thedeformation of the ball crystal is the two or third growth brilliant arm root blow-out ball upcrystal phase give priority to. |
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