摘要
基于半固态流变铸造过程中流变与凝固强耦合的特点,提出了流变碰撞形核和流变合并长大的流变凝固理论。理论认为,在强烈流动条件下,经典的结构起伏形核理论不再适用,液态金属中原子团簇(晶胚)间的碰撞合并形核成为主要形核机制,流变形核率是经典结构起伏形核率和流变碰撞形核率之和;在强烈流变条件下,初生固相之间接触碰撞,进而合并粗化长大是流变成形过程初生相长大与演变的主要机制。基于该流变凝固理论,提出了随流半固态铸造技术(SSMF)。该技术包括半固态熔体的流变制备、流变充型和流变凝固成形3个基本步骤。液态金属在流变充型的过程中随流形核和长大,并在随后的半固态成形过程发生演变和剩余液相的凝固。实现了浆料制备与工件的半固态成形制造无缝连接,能够从根本上解决半固态浆料制备、输送与充型过程的氧化、吸气等问题,是材料制备与成形一体化的零件成形新技术。
Based on the characteristics of strong coupling between rheology and solidification in semi-solid rheological casting process,the rheological solidification theory of rheological collision nucleation and rheological merging growth was proposed.The theory claims that the classical structural undulating nucleation theory is no longer applicable under the condition of strong flow,and nucleation mechanism is dominated by collisional merging nucleation between atomic clusters(crystal embryos)in liquid metal instead,where the rheological nucleation rate is the sum of the classical undulating nucleation rate and the rheological collision nucleation rate.In the presence of strong rheological conditions,the primary solid phases contact and collide firstly,then become coarsening and grow,which is dominant mechanism for growth and evolution of the primary phase during rheological forming process.On this basis,the semi-solid metal forming with flow(SSMF)was put forward.The basic steps cover rheological preparation,rheological filling and rheological solidification.During the rheological filling process,the liquid metal nucleates and grows with the manifold,and evolution as well as solidification of the residual liquid phase occur in the subsequent semi-solid forming process.In conclusion,a new technology that integrates the material preparation and forming is manifested,which achieves a seamless connection between slurry preparation and semi-solid forming manufacturing of workpiece,fundamentally solving the problems of oxidation and air entrainment during preparation,transportation,and filling process of semi-solid slurry.
作者
邢书明
高文静
潘琦俊
胡柏丽
王超
Xing Shuming;Gao Wenjing;Pan Qijun;Hu Baili;Wang Chao(School of Mechanical,Electronic and Control Engineering,Beijing Jiaotong University;Wuhu Hetian Automobile Industry Co.,Ltd.)
出处
《特种铸造及有色合金》
CAS
北大核心
2023年第6期721-728,共8页
Special Casting & Nonferrous Alloys
基金
中央高校基本科研业务费专项资金资助项目(2020YJS146)。
关键词
流变凝固
流变形核
流变长大
随流半固态成形
Rheological Solidification
Rheological Nucleation
Rheological Growth
SSMF
