Pr对Sn-Cd包晶合金定向凝固组织的影响

Effect of praseodymium on directional solidification microstructure of Sn-Cd peritectic alloys

为了解Pr对Sn-Cd包晶合金凝固组织的作用,在不同抽拉速率下对Sn-Cd-Pr合金进行定向凝固实验.采用光学显微镜、扫描电子显微镜(SEM)和能谱分析(EDS)研究了Pr对Sn-Cd包晶合金凝固组织的影响.研究发现:对于Sn-1.8%Cd过包晶合金,在2μm/s时0.5%的Pr增加了包晶相β的体积分数;在4μm/s时凝固组织明显细化.对于Sn-0.65%Cd亚包晶合金,在4μm/s时Pr的加入促进了平→胞界面的转变;在16μm/s时随着Pr含量的增大,凝固组织逐渐细化;在100μm/s时Pr含量的增大使凝固组织仅有微弱的细化.研究表明,Pr的加入可以改变组成相的体积分数、细化组织以及减小界面稳定性.

To understand the effect of praseodymium（Pr） on solidification structures of Sn-Cd alloys, the alloy Sn-Cd-Pr is experimented by directional solidification at different withdrawing rates. The effect of Pr on solidifi- cation structures of Sn-Cd alloys is studied by using optical microscope, scanning electron microscope （SEM） and energy spectrum analysis（EDS）. For Sn-1.8 wt% Cd hyperperitectic alloy, the amount of the peritectic 13 phase of Sn-1.8 wt% Cd with 0.5 wt% Pr increases at the rate of 2 μm/s, and the microstructure refines dis- tinctly at the rate of 4 μm/s. For Sn-0.65 wt% Cd hypoperitectic alloy, the addition of Pr promotes the planar cellular transition at the rate of 4 μm/s. The microstructure refines by degrees with the increasing of Pr con- tent at the rate of 16 μm/s. Howewever,the microstructure changes unsignificantly with the increasing of Pr con- tent at the rate of 100 μm/s. The addition of Pr can change the volume fraction of phase,refine the microstruc- ture and decrease the interface stability.