含金属氟化物的熔剂与铝液的反应热力学分析  

Experimental Research and Thermodynamics Analysis of Reactions between Aluminum Melt and Salt Fluxes Containing Metal Fluorides

作　　者：王火生[1,2] 傅高升 孙泽棠[3] 程超增 宋莉莉[1] 

机构地区：[1]福州大学材料科学与工程学院 [2]福建工程学院材料科学与工程学院 [3]福州大学机械工程及自动化学院

出　　处：《特种铸造及有色合金》2017年第11期1258-1262,共5页Special Casting & Nonferrous Alloys

基　　金：国家科技部国际合作项目(2015DFA71350);福建省科技计划重点项目(2012H0006)

摘　　要：通过热力学分析与试验研究了含金属氟化物的熔剂与A356铝合金中主要元素的反应,以及对铝合金组织与成分,熔剂组成相的影响,采用SEM、EDS和XRD进行组织和成分分析。结果表明,金属氯化物与A356主要元素的置换反应平衡常数大多低于氟化物,表明熔剂中的氯化物具有更好的化学稳定性。含NaF、SrF_2、BaF_2的熔剂中,氟化物较易与A356合金中的Al或Mg反应,在铝熔体中生成游离态Na、Sr、Ba原子,对共晶Si相有显著变质作用。含Na3AlF6的熔剂也会与铝液反应生成少量Na原子,对共晶Si相有一定的变质作用。含AlF_3、MgF_2和CaF_2的熔剂对A356铝合金组织没有明显影响。含NaF和BaF_2的熔剂可分别生成新的KMgF_3和BaFCl相,其他氟化物对熔剂成分没有明显影响。MgF_2、CaF_2、SrF_2和BaF_2由于熔点和密度高,容易在A356铝合金中残留。The reaction between salt fluxes containing metal fluorides and main elements in A356 alloy was investigated by thermodynamics analysis and experiments,and its influence on microstructure and constituent of Al alloy and the phase of fluxes were analyzed by SEM,EDS and XRD.The results reveal that the equilibrium constants of displacement reactions between main elements of A356 alloy and metal chlorides are mostly lower than those of metal fluorides,which indicate that metal chlorides are more stable than fluorides in salt fluxes.NaF,SrF2 and BaF2 in the fluxes can react easily with Al or Mg and generate the divorced atoms in Al melt,such as Na,Sr,Ba,to modify eutectic silicon significantly.Na3 AlF6 fluxes can also react with Al and generate trace the divorced Na atoms to modify eutectic silicon slightly.However,influences of AlF3,MgF2 and CaF2 on microstructures of A356 alloy can be ignored.Metal fluorides not exhibit measurable effects on the phase of salt fluxes while NaF and BaF2 can generate new phases KMgF3 and BaFCl in salt fluxes,respectively.MgF2,CaF2,SrF2,BaF2 would remain in A356 alloy because of their high densities and melting points,which could affect the constituents of alloy.

关 键 词：熔剂 金属氟化物 A356铝合金 热力学 显微组织 

分 类 号：TG146.21[一般工业技术—材料科学与工程] TG111.3[金属学及工艺—金属材料]