稀土La+Sr复合变质对ZL101A合金组织的影响

Effect of Complex Modification of Rare Earth(La+Sr) on Structure of ZL101A

研究了稀土La+Sr复合变质对ZL101A合金共晶硅形状的影响。分析了复合变质剂加入量、变质温度、保温时间和冷却速度对合金组织的影响。结果表明,当Sr加入量为0.015%时,加入0.2%的La即可达到很好的变质效果,显著减少了稀土用量。另外,复合变质不但解决了Sr的潜伏期问题,而且还使ZL101A合金在变质时对温度的敏感性降低,在720℃就可完全发挥变质作用。复合变质后,晶粒能够细化到0.5 mm,比单一稀土细化效果更好。同时得出,冷却速度越快变质效果越好。

The effects of La and Sr on the stereo morphology of ZL101A eutectic silicon were studied. The adding amount, adding temperature and holding time of complex modification were considered as the influencing factors on the structure and grain size of alloy and analyzed, together with modifying by single Sr. Whilst, the effect of cooling rate on the structure of alloy was also investigated. The experimental results show that the consumption of rare earth can be decreased and fine modification is obtained with complex modification of 0.015%Sr and 0.2%La. In addition, the incubation time of Sr is shortened by complex modification. Complex modification reduces the temperature sensitivity of the alloy and the finest modification effect is available at 720℃. Complex modification also has better impact on grain refinement than that of single La or Sr. The grain size can be decreased to 0.5 mm and the modification effect will be better with increasingly cooling rate.