TiAl_3对TiC粒子在铝熔体中沉淀特性的影响机理

Effect Mechanism of TiAl_3 on the Precipitation of TiC Particles in Aluminum Melt

采用金相显微镜(MEF3)、电子探针(EPMA)等研究TiC和TiAl3细化工业纯铝时TiAl3的存在对TiC在铝熔体中沉淀特性的影响规律,分析其影响机制。结果表明:TiC在铝熔体中单独存在时沉淀速率快,在较短时间保温后,大量TiC发生沉淀,从而限制其异质形核作用;当TiC和TiAl3在铝熔体中共同存在时,TiC沉淀速率变缓,在较长时间保温后,只有少量TiC发生沉淀,表现出较强形核能力和抗晶粒细化衰退能力。其影响机理是:TiAl3在铝熔体中增大了TiC粒子的沉降阻力,使得TiC粒子沉降速率变缓而在凝固时成为α(Al)的异质形核质点。Al-Ti-C合金细化作用衰减是由TiC发生沉淀引起。

The effect of TiA13 on the precipitation of TiC particles in aluminum melt was studied when TiC and TiA13 refining industry aluminum, and the mechanism was discussed using MEF3 and EPMA. The results show that TiC particles deposit quickly and have poor nucleation capability when TiC is used as the a（A1） nucleation phase only, but when TiC and TiA13 common as the a（A1） nucleation phase, TiC particles deposit more and more slow. Even after long time, there was only a small a- mount of precipitation. It demonstrated better nucleation and higher resistance to grain refining fa- ding. The reason is that TiA13 increase the settlement resistance of TiC particles. The refinement effect fading of A1-Ti-C master alloy is caused by TiC precipitation.