添加重熔料及稀土钇对ZL205A合金铸态组织、热裂性能及凝固特性的影响

Effects of Scraps and Yttrium on the As-Casting Microstructure, Hot Tearing and Solidification Characteristics of ZL205A Alloy

研究重熔料及稀土钇对ZL205A合金铸态组织、热裂性能及凝固特性的影响。结果表明:单独和复合添加重熔料及稀土钇都能够细化合金组织,使之变得更加均匀、细小。单独添加重熔料对ZL205A合金相的组成没有影响,但是提高了ZL205A合金凝固过程中液相线温度,增大了固液共存区间,进而增加合金的热裂倾向性;单独添加稀土钇和复合添加重熔料及稀土钇均可使合金凝固过程中液相线温度降低,减小固液共存区间从而有效地改善合金的热裂倾向性,使得热裂抗力由原料ZL205A合金的330N左右分别提高至450和670N左右。除此之外,添加稀土钇后,三角晶界处出现了灰色块状富钇相。

The effects of scraps and yttrium on the as-casting microstructure, hot tearing susceptility and solidification characteristics of ZL205A alloy were investigated. The results indicate that microstructure of ZL205A alloy was refined by adding scraps and yttrium. The phase composition of ZL205A alloy did not change after adding scraps. However, the scrap addition increased the solid-liquid coexistence zone during solidification of ZL205A alloy and the hot tearing susceptility. With yttrium or yttrium and scraps co-additions, the solid-liquid coexistence zone decreased and the hot tearing susceptility was improved, and the hot tearing force was improved to about 450 N and 670 N compared with 330 N primary alloy. Besides, yttrium-rich phase appeared in the triangular grain boundary of Z1205A alloy after adding yttrium.