alsi二元合金熔体混合凝固组织和性能分析word格式论文.docxVIP

摘要过共晶铝硅合金因为凝固组织中具有初生硅相从而使材料增强，但又因为初生硅通 常情况下为粗大的板条状而破坏塑性。亚共晶铝硅合金的强度、硬度不如过共晶铝硅合 金，但塑性和韧性优于过共晶铝硅合金。如果能够在同一种铝硅合金中既获得过共晶组 织又获得亚共晶组织，这将会给材料的应用带来极大的方便。本文采用半固态的过共晶铝硅合金与液态的亚共晶铝硅合金熔体混合的方法，探讨 了在同一合金中获得兼具亚共晶组织和过共晶组织特征的复合组织的过程。实验结果表 明：本文所用的熔体混合法能够在同一合金中获得兼具亚共晶和过共晶特征的复合组 织。此法对初生硅有细化作用。混合后所得合金的韧性相对常规的过共晶合金得到提高， 强度和硬度相对常规亚共晶合金得到提升。通过改变熔体的温度以及熔体的混合量，探讨了凝固组织的变化。实验结果表明： 亚共晶铝硅合金熔体温度越高，初生硅溶解越多、尺寸越细小。在相同的熔体温度条件 下，增加亚共晶铝硅合金熔体的量，对初生硅的溶解有一定的促进作用。通过改变熔体混入的方式，探讨了凝固组织的变化。实验结果表明：亚共晶铝硅合 金采用多孔雨淋的方式混入半固态过共晶合金中时，在相同的熔体温度和混合量的条件 下，初生硅的搭接现象有改善。通过在不同阶段添加变质剂，探讨变质剂的加入和熔体混合两者共同对凝固组织的 影响。实验结果表明：在熔体混合之后添加变质剂，初生硅的细化效果较未加变质剂的 好，分布也较均匀。将添加了（NaF+NaCl）变质剂的亚共晶铝硅合金熔体与添加（P+S+Al+KCl）变质剂的过共晶铝硅合金混合，共晶硅和初生硅均得到细化。关键词：熔体混合；复合组织；初生硅；溶解；变质剂IAbstractHypereutectic Al-Si alloy was strengthened because it has the primary silicon phase in the solidifying structure ,but because of the primary silicon is normally thick plate to damage plasticity. Strength and hardness of the hypoeutectic Al-Si alloy is lower than the hypereutectic Al-Si alloys, but the plasticity and toughness is better than that of hypereutectic Al-Si alloys. If can be obtain both hypereutectic structure and hypoeutectic structure in the same Al-Si alloy, it will brings great convenience to the applications of the materials.In this thesis, through mixing semisolid hypereutectic Al-Si alloy and liquid hypoeutectic Al-Si alloy melt . At the same time get hypereutectic structure and hypoeutectic structure in the same alloy are discussed. The experimental results show that the melt mixing method used in this paper can at the same time get the hypereutectic and hypoeutectic composite microstructure. This method is able to refine the primary silicon phase. Preparation of the alloy in this way has the toughness relatively conventional hypereutectic alloy was improved, strength and hardness of relatively conventional hypoeutectic alloy was improved.By changing the melt temperature and quality, the changes of solidified structure are discussed. Experimental results show