半固态铝合金浆料的复合制备和流变成形研究  

Research on the Composite Slurry Preparation and Rheocasting of Aluminum Alloy

作　　者：毛卫民[1] 汤国兴[1] 白月龙[1] 赵振铎[1] 

机构地区：[1]北京科技大学材料科学与工程学院

出　　处：《特种铸造及有色合金》2007年第S1期330-333,共4页Special Casting & Nonferrous Alloys

基　　金：国家863计划项目(2006AA03Z115);国家重点基础研究发展规划项目(2006CB605203);国家自然科学基金项目(50374012)

摘　　要：利用短时弱电磁搅拌和低过热度制备了半固态AlSi7Mg铝合金浆料,随后对该浆料进行了均热处理,并探讨了浆料温度、压射比压与压射速度对铝合金浆料流变成形过程的影响。制备结果表明,在630~650℃下浇注,同时附以短时低强度电磁搅拌,AlSi7Mg合金中的初生α-Al呈现为球状,个别的初生α-Al呈现为蔷薇状;在固液两相区进行均热处理时,促进了初生α-Al的熟化作用,使初生α-Al进一步球化和粗化。成形结果还表明:浆料温度、压射比压和压射速度对半固态AlSi7Mg合金浆料的充填性影响较大,压射比压和压射速度越大及浆料温度越高,型腔越容易充满;铁芯位置距离内浇道越近,越有利于半固态AlSi7Mg合金浆料的充填;对于试验的钥匙铸件,只要浆料温度≥585℃,或压射比压≥20MPa,或压射速度≥1.73m/s,半固态AlSi7Mg合金浆料都可充满型腔。流变成形铸件的组织分布很均匀,表明采用低过热度浇注和弱电磁搅拌相结合所制备的半固态AlSi7Mg铝合金浆料适合流变成形,有利于获得高质量的压铸件。The semisolid slurry of AlSi7Mg alloy was prepared by being poured at a low superheat and stirred by an electromagnetic field at a low power for a short time,and then the slurry was further soaked for proper time and finally rheoformed into a key-shaped die cavityin this paper.The influence of slurry temperature,specific pressure and injection speed on the rheoforming process was also studied.The experimental results show that if the melt of AlSi7Mg alloy is poured at 630 ℃ or 650 ℃and meanwhile stirred by an electromagnetic field at a low power for a short time,the most primary α-Algrains solidified in the slurry are spherical and only a few are rosette-like.If the slurry is then homogeneously soaked in the liquidus-solidus range for some time,the ripening of primary α-Alis developed further and it becomes more spherical and larger.The experimental results also show that the slurry temperature,injection pressure and speed have great influence on the filling ability.The higher the slurry temperature,injection pressure and speed,the higher the slurry filling ability,and the shorter the core distance from the ingate,the more easily the die cavity is filled.With the given key-shaped casting,if only the slurry temperature should be equal to or more than 585 ℃,or the injection pressure is equal to or more than 20 MPa,or the injection speed should be equal to or more than 1.73 m/s,the key-shaped die cavity can be filled completely.The microstructuraldistribution in the casting is very homogeneous and it shows that the slurry prepared by above-mentioned method is very suitable for rheoforming and helpful to obtaining high quality castings.

关 键 词：半固态 电磁搅拌 流变成形 显微组织 ALSI7MG合金 

分 类 号：TG249.9[金属学及工艺—铸造]