退火温度对Zr-3.3Si合金显微组织和力学性能的影响

Effect of annealing temperature on microstructure and mechanical properties of Zr-3. 3Si alloy

采用光学显微（OM）,X-射线衍射仪（XRD）,扫描电镜（SEM）对铸态以及分别在600、700、800和900℃退火处理30 min的Zr-3.3wt%Si合金的显微结构进行了研究。结果表明：铸态Zr-3.3Si合金的相组成主要为α-Zr、Zr5Si3和Zr2Si,合金退火处理后,没有新的衍射峰出现,但衍射峰向高角度有轻微的偏移。在600℃退火时,粗大的四边形Zr5Si3相数量减少,而长条状的硅化物没有明显变化;退火温度为700℃时,四边形硅化物数量增多,尺寸细小、分布均匀;温度继续升高,硅化物的尺寸没有减小,反而增加。力学性能研究表明：在700℃退火时合金的抗压强度和屈服强度最高,分别达到1249 MPa和1094 MPa,硬度值达到最大,约353 HV0.2,但塑性应变是最低的,仅有6.2%。

The microstructure of Zr-3. 3 wt% Si alloy as-cast and as-annealed at 600,700,800 and 900 ℃ respectively for 30 min was studied by means of optical microscopy（ OM）,X-ray diffractometry（ XRD） and scanning electron microscope（ SEM）. The results show that the phases of as-cast Zr-3. 3 Si alloy consist of α-Zr、Zr5 Si3 and Zr2 Si. After annealing treatment,new diffraction peaks are not discovered,and the diffraction peaks slightly shift to high angle. After annealing at 600 ℃,the amount of coarse tetragonum Zr5 Si3 phase reduces,and the rod-like silicides changes a little. After annealing at 700 ℃,the amount of tetragonum silicides increases,which are fine and uniformly distributed. With the increase of temperature,the size of silicides does not decrease but increases. The mechanical properties of samples show that the compressive strength and yield strength of the alloy are the highest at 700 ℃,reaching 1249 MPa and 1094 MPa respectively.At the same time,the hardness value reaches 353 HV0. 2,while the plasticity is the lowest about 6. 2%.