【作者】 熊红玲；

【导师】 吴树森；

【作者基本信息】 华中科技大学 ， 数字化材料成形， 2007， 硕士

【摘要】 Al-Si合金具有优良的铸造性能和力学性能,是铸造铝合金中最重要的一种,在工业中应用非常广泛。但是铸造铝硅合金中共晶硅通常呈层片状,严重割裂基体,使合金力学性能特别是塑性显著降低。因此工业中通常对合金熔体进行变质处理来提高合金性能。目前国内工业生产中用来检测合金变质效果的方法通常检测周期长,操作不方便,不适合在线检测。本课题组自主研究开发了一种快速、高精度判断合金变质效果的热分析系统。为了建立与之相匹配的热分析模型,本课题对ZL104和ZL101合金的锶变质和钠盐变质效果进行了热分析研究,建立了合适的判据。本文采用ZL104、ZL101作为研究对象,以Al-10Sr中间合金和四元Na盐（30%NaF+50%NaCl+10%KCl+10%Na₃AlF₆）作为变质剂,研究合金变质等级与热分析参数△T_EG之间的对应关系。ZL104采用Sr变质时,变质等级与热分析参数△TEG（变质前后共晶温度的降低值）之间存在良好的对应关系,当△T_EG大于8℃时,合金变质等级在5级以上,当△T_EG小于5℃时,合金无明显的变质效果,变质等级与△T_EG的对应关系可用S型曲线表示;ZL104用Na盐变质,未出现过变质现象时,△T_EG大于5℃,合金变质等级在5级以上;△T_EG小于2℃时,合金接近未变质组织,变质等级与△T_EG之间对应关系可用多项式表示;ZL101用Na盐变质,未出现过变质现象时,△T_EG大于5℃,合金变质等级在5级以上,△T_EG小于3℃,合金接近未变质组织,变质等级与热分析参数△T_EG之间对应关系可用S型曲线表示;本文还研究了Al-5Ti-B和Al-10Sr对ZL104联合作用时,Al-5Ti-B对热分析参数△T_EG与变质等级之间的对应关系的影响,Al-5Ti-B的加入只是减少了合金中有效Sr含量,不改变Sr的变质机理,即Al-5Ti-B的加入不影响△T_EG与变质等级之间的对应关系。最后用Visual C++在课题组开发的热分析软件中建立数据库,保存所有实验数据,为后续研究提供参考。更多还原

【Abstract】 Due to their excellent castability and good mechanical properties, aluminum-silicon alloys are the most important and most widely used aluminum alloy. However, a unmodified alloy contains large brittle silicon flakes which greatly aggravate the mechanical properties, especially the plastic properties. The plastic properties usually improved by means of modification in industry.The methods evaluated the modification level in industry of China are always time-consuming, and low precision. A fast, high precision thermal analysis system has been developed in this research program. In order to establish thermal analysis models matching with the system, ZL101 and ZL104 alloys were modified by strontium or sodium in this paper, the model between modification level and characteristic parameter was established.ZL104 and ZL101 alloy were researched; the modifier is Al-10Sr or Na salt. When ZL104 was modified by Sr, if△T_EG is above 8℃, the modification level is five to six, and if△T_EG is lower than 5℃, the alloy is unmodified, the characteristic parameter△TEG （the depression of eutectic growth temperature between modified and unmodified alloy） and modification level agreed with S-style curve relationship.when ZL104 was modified by Na salt, if△T_EG is above 5℃, the modification level is five to six, if△T_EG is lower than 2℃, the alloy is unmodified, the characteristic parameter△T_EG and modification level agreed with polynomial curve relationship.when ZL101 was modified by Na salt, if△T_EG is above 5℃, the modification level is five to six, if△T_EG is lower than 3℃, the alloy is unmodified, the characteristic parameter△T_EG and modification level agreed with S-style curve relationship. Alloy is always refined and modified together in industry. The effect of Al-5Ti-B on hypoeutectic alloy which modified by Sr is also researched in this paper. Al-5Ti-B just changes the level of Sr in the melt but not the modification mechanism, so it didn’t change the relationship between△T_EG and modification level.Finally, a database built by Visual C++ was established in the thermal analysis software. This database was used for memoring data and giving reference for later research.更多还原