稀土元素Gd对NiAl合金显微组织和力学性能的影响

EFFECT OF Gd ON THE MICROSTRUCTURES AND PROPERTIES OF NiAl INTERMETALLICS

研究了不同Gd含量对二元NiAl合金组织以及室温和1100℃压缩性能的影响.结果表明,稀土Gd在NiAl中的固溶度很小,在合金晶内及晶界大量析出一种脆硬的新相——富Gd相.由于Gd的固溶强化和适量富Gd相产生的第二相强化,使得含0.10Gd合金的室温压缩强度高于二元NiAl的,而晶界上析出较多的富Gd相又使得含0.25Gd和0.50Gd合金的室温压缩强度较低;Gd的净化基体作用使得NiAl-Gd合金的室温压缩塑性高于二元NiAl的室温压缩塑性.含Gd合金在1100℃压缩,亦未出现应变软化现象.

The effects of various rare earth Gd behavior of binary NiAl intermetallic compound have content on the microstructure and compressive been investigated by using SEM, XRD, EPMA and compression tests. The results show that a brittle Gd-rich phase was found and precipitated within grains and on grain boundaries. Proper Gd addition can improve the room temperature compressive strength of NiAl due to solid solution strengthening and second phase strengthening, but too much Gd-rich phases on the grain boundaries lead to the poor room temperature strength. The interaction between Gd and O and S increases room temperature compressive ductility of NiAl-Gd alloys. No strain softening phenomena was observed in high temperature compressive tests of the alloys with Gd.