7050铝合金倾斜板流变压铸的显微组织及力学性能

Microstructure and solidification behavior of rheological die-casting of 7050 aluminum alloy inclined plate

采用倾斜板流变压铸工艺制备7050铝合金,研究了合金的组织演变及形成机制。比较传统压铸与流变压铸的组织与性能。结果表明,随着浇注温度的降低,晶粒的圆整度和固相率提高,初生α-Al晶粒得到了细化。同时二次凝固α-Al组织变得更加细小圆整。在相同浇注条件下,随着充型距离的增加,过冷度增加,初生α-Al晶粒的平均晶粒直径减小。初生晶粒形成机制主要为激冷形核和枝晶破碎。与传统压铸相比,倾斜板流变压铸工艺能够得到细小等轴、近球状的组织,并且具有更优异的力学性能。

7050 aluminum alloy was prepared by inclined plate rheological die-casting process,and the microstructure evolution and formation mechanism of the alloy were studied.The results show that compared with the traditional die-casting sample,the inclined plate rheological die-casting process obtains a fine equiaxial,nearly spherical structure.With the decrease of pouring temperature,the roundness and solid-phase rate of the grains increased,and the primaryα-Al grains were refined.At the same time,the secondary coagulationα-Al tissue becomes more fine and round.Under the same pouring conditions,with the increase of filling distance,the subcooling degree increased,and the average grain diameter of the primaryα-Al grain decreased.The formation mechanism of primary grains is mainly cold nucleation and dendrite fragmentation.