原位自生TiB_(2)颗粒作用下偏晶Al_(62.5)Sn_(28.7)Cu_(8.8)合金的液相分离规律研究  

Phase separation mechanism of liquid Al_(62.5)Sn_(28.7)Cu_(8.8) monotectic alloy modulated by in situ synthesized TiB2 particles

作　　者：王宝剑 翟薇[1] 吴文华 魏炳波[1] WANG BaoJian;ZHAI Wei;WU WenHua;WEI BingBo(School of Physical Science and Technology,Northwestern Polytechnical University,Xi'an 710072,China)

机构地区：[1]西北工业大学物理科学与技术学院,西安710072

出　　处：《中国科学：技术科学》2022年第11期1679-1691,共13页Scientia Sinica(Technologica)

基　　金：国家自然科学基金(批准号:52088101,51922089和51727803);陕西省重点研发计划(编号:2020ZDLGY13-03)资助项目。

摘　　要：在三元Al_(62.5)Sn_(28.7)Cu_(8.8)偏晶合金中原位反应合成不同含量的TiB2颗粒,研究了其对液相分离过程中第二液相L2(Sn)形核、长大和迁移的作用机制.实验表明,当掺杂1%TiB_(2)颗粒时,液相分离引发的宏观偏析程度显著降低,而进一步增加颗粒含量时,宏观偏析降低程度趋缓.同时,掺杂TiB2颗粒后初生θ(Al_(2)Cu)相和第二(Sn)相组织明显细化.在液相分离过程中,与合金熔体具有良好润湿性的原位自生TiB2颗粒促进了第二L_(2)(Sn)相的异质形核,通过阻碍元素扩散和液滴迁移限制L_(2)(Sn)相的扩散长大,并改变合金熔体的黏度和密度以及L2(Sn)液滴形状,从而降低Stokes沉降速度,最终减弱组织偏析.因此,合金拉伸力学性能随着原位自生TiB2颗粒质量分数的增加而显著提高.TiBparticles with different contents were in situ synthesized in liquid Al_(62.5)Sn_(28.7)Cu_(8.8) monotectic alloy.The nucleation,growth,and migration mechanisms of the secondary liquid L(Sn) phase during liquid phase separation were investigated by experimental observations and theoretical analyses.When 1% TiB_(2) particles were added to this ternary monotectic alloy,macrosegregation induced by liquid phase separation was significantly reduced,whereas,when TiBcontent was further increased,there was only a little enhancement in the reduction of macrosegregation degree.Meanwhile,the secondary (Sn) phase and primary θ(Al_(2)Cu) phase structures were refined after TiB_(2) particles were incorporated into the alloy melt.During liquid phase separation,the in situ synthesized TiBparticles promoted the heterogeneous nucleation of the secondary L_(2)(Sn) phase,resulting in the formation of a large number of L_(2)(Sn) droplets.In addition,TiBparticles restricted the diffusion growth of L(Sn) droplets by impeding element diffusion and droplet migration,and hindered Stokes sedimentation of L(Sn) droplets by changing the viscosity and density of the alloy melt as well as the droplet shape.The tensile property of monotectic Al_(62.5)Sn_(28.7)Cu_(8.8) alloy was improved as TiBcontent increased.

关 键 词：偏晶合金 TiB_(2)颗粒 液相分离 Stokes运动 组织偏析 

分 类 号：TG132[一般工业技术—材料科学与工程]