On the mechanism of Si-promoted destabilization of TiC_(x)particles in Al alloys  

作　　者：H.Dong Y.C.Guo Y.Z.Chen F.Xia Q.Q.Guo Q.Chen G.L.Li J.Y.Zhao Y.Zhong J.P.Li 

机构地区：[1]School of Materials and Chemical Engineering,Xi’an Technological University,Xi’an 710021,China [2]State Key Lab.of Solidification Processing,Northwestern Polytechnical University,Xi’an 710072,China [3]School of Science,Xi’an University of Science and Technology,Xi’an 710054,China

出　　处：《Journal of Materials Science & Technology》2023年第34期17-26,共10页材料科学技术（英文版）

基　　金：the financial supported from the Key R&D Program of Shaanxi Province,China(No.2020ZDLGY13-01);the innovation team program of material developing and application of key engine components(No.K20220185);the National Natural Science Foundation of China(Nos.52101049,52234009 and 52071262).

摘　　要：TiC_(x)is an excellent composite strengthening particle and grain refiner for Al alloys.However,the stability of TiC_(x)is poor when solute Si exists in Al alloy melts,which significantly depresses its strengthening and grain refining effects.In this work,the destabilization mechanisms of the TiC_(x)particles in Al-Si alloy melt with a composition of Al-7Si-7.5TiC were explored via experiments,first-principles calculations and thermodynamic calculations.The experimental results show that Si atoms diffuse into TiC_(x)and Ti atoms are released into the Al melt to form a Ti-rich transition zone during the insulation of TiC_(x)in Al-Si melt,and the TiAlySiz and Al_(4)C_(3)phases are solidified in the Ti-rich zone and at Ti-rich zone/TiC_(x)interface,respectively.The first principles calculations show that the low formation energy of C vacancies facilitates the rapid diffusion of Si atoms in TiC_(x),while the doping of Si atoms reduces the energy barrier of diffusion of Ti atoms in TiC_(x)and promotes the formation of Ti-rich zones.The thermodynamic calculations show that the wide crystallization temperature range of the destabilized product TiAlySiz phase is the key to continuous decomposition of TiC_(x)particles.In addition,the driving force of the main destabilization reaction of TiC_(x)in the Al-Si alloys is about 44 times higher than that in the Al alloys without Si addition.This indicates that the presence of solute Si remarkably promotes the subsequent decomposition process of TiC_(x)in the Al-Si alloy melts.

关 键 词：Al-Si alloy TiC_(x)particles DESTABILIZATION First principles calculations Thermodynamics 

分 类 号：TG146.32[一般工业技术—材料科学与工程]