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为研究DZ483合金在凝固过程中的元素偏析行为对糊状区内液相密度的影响,采用等温凝固结合水淬法对合金进行不同温度下的凝固实验.利用OM和SEM观察试样的凝固组织,利用EDS测量固相和剩余液相的元素含量,并根据剩余液相的成分计算其密度.结果表明,DZ483合金的开始凝固温度略低于1335℃,在1325℃液相中开始析出富含Ta和Ti的MC;W和Co为负偏析元素,Mo,Ta和Ti为正偏析元素,而Al和Cr几乎不发生偏析;剩余液相的密度随温度降低基本呈下降趋势,但在1325至1315℃之间有所回升.计算结果表明,温度对液相密度的影响很小,合金元素的偏析对液相密度的影响占主要地位.其中,Mo和Ta的偏析导致液相密度增加,而Ti和W的偏析导致液相密度明显降低.备合金元素的偏析对密度变化的贡献由大到小顺序为:Ti>Ta>W>Cr>Mo>Al>Co.MC的形成消耗了大量的Ti和Ta,对合金元素的偏析造成一定的影响,从而导致液相密度在1325至1315℃之间有所增加.
In order to study the influence of elemental segregation behavior of DZ483 alloy on the liquid phase density in the pasty area, the solidification experiment of the alloy at different temperatures was carried out by isothermal coagulation combined with water quenching.The OM and SEM were used to observe the solidification structure , The elemental content of the solid phase and the remaining liquid phase was measured by EDS and the density was calculated according to the composition of the remaining liquid phase.The results showed that the initial solidification temperature of DZ483 alloy was slightly lower than 1335 ℃ and began to precipitate in the liquid phase at 1325 ℃ Ta and Ti; W and Co are negative segregation elements, Mo, Ta and Ti are positive segregation elements, while Al and Cr hardly segregate; the density of the remaining liquid phase decreases with temperature decreasing, but in the period from 1325 to 1315 ℃ .The calculated results show that the influence of temperature on the liquid density is very small and the segregation of alloying elements plays a dominant role on the liquid density.The segregation of Mo and Ta leads to the increase of liquid density, The segregation of Ti and W led to a significant decrease in the liquid density.The contribution of segregation of alloying elements to the density change from high to low is as follows: Ti> Ta> W> Cr> Mo> Al> Ti and Ta, the segregation of alloying elements have a certain impact, from Resulting in an increase in liquid density between 1325 and 1315 ° C.