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采用氟盐法和对掺法成功制备了Al-5Ti-1B-4Sr中间合金,采用X射线衍射(XRD)和扫描电镜(SEM)分析了Al-5Ti-1B-4Sr中间合金的组织及相组成。通过改变Al-5Ti-1B-4Sr中间合金细化变质保温时间,采用微观组织分析和宏观组织分析方法,研究了Al-5Ti-1B-4Sr中间合金对Al-8Si亚共晶铝硅同时细化和变质的效果。研究结果表明,Al-5Ti-1B-4Sr中间合金中含有Al_3Ti相、TiB_2相和Al_4Sr相,Al-5Ti-1B-4Sr中间合金对亚共晶铝硅合金有良好的同时细化变质效果。Al-5Ti-1B-4Sr中间合金可使共晶硅从针状或板片状形貌转变为纤维状或块状。与未变质试样相比,细化变质时间为10 min时,Al-8Si合金中针状或板片状共晶硅显著减少;变质时间超过20 min时,看不到针状或板片状共晶硅存在;当变质时间达到80 min时,部分针状或板片状共晶硅再次出现。随着Al-5Ti-1B-4Sr细化变质保温时间的变化,α-Al的二次枝晶臂间距和共晶团尺寸先减小后增大,细化变质保温时间为30 min时效果最好。Al-5Ti-1B-4Sr中间合金对亚共晶铝硅合金细化变质的孕育期为10~20 min,衰退期为60 min。
Al-5Ti-1B-4Sr master alloy was successfully prepared by fluorine salt method and doping method. The microstructure and phase composition of Al-5Ti-1B-4Sr master alloy were analyzed by X-ray diffraction and scanning electron microscope . The Al-5Ti-1B-4Sr master alloy Al-8Si hypoeutectic Al-Si alloy was refined at the same time by changing the aging time of Al-5Ti-1B-4Sr master alloy and using microstructure analysis and macrostructure analysis method. And metamorphic effect. The results show that Al_3Ti phase, TiB_2 phase and Al_4Sr phase are contained in the Al-5Ti-1B-4Sr master alloy, and the Al-5Ti-1B-4Sr master alloy has good metamorphism and metamorphic effect on the hypoeutectic Al-Si alloy. Al-5Ti-1B-4Sr master alloy can be eutectic silicon from acicular or plate-like morphology into fibrous or massive. Compared with the unmodified samples, the amount of acicular or lamellar eutectic silicon in Al-8Si alloy decreased remarkably when the metamorphism time was 10 min. When the modification time exceeded 20 min, the acicular or lamellar Eutectic silicon exists; when the metamorphic time reached 80 min, some acicular or lamellar eutectic silicon appeared again. With the change of Al-5Ti-1B-4Sr refinement and holding time, the secondary dendrite arm spacing and eutectic size of α-Al first decreased and then increased, and the effect of refining and holding time was 30 min it is good. Al-5Ti-1B-4Sr master alloy hypoeutectic Al-Si refinement of the incubation period of 10 ~ 20 min, the recession period of 60 min.