高纯金属钪的退火工艺

Annealing process of high purity scandium metal

采用硬度测量和光学显微镜观察,研究了不同退火温度对锻压加工后高纯金属钪硬度和微观组织的影响。结果表明,在相同退火时间下,随着退火温度的提高,金属钪的平均晶粒度总体呈上升趋势,硬度先降低后趋于平稳。当退火温度低于725℃时,回复再结晶过程相对缓慢,平均晶粒度增长有限,而硬度随退火温度的升高持续降低,在725℃时达到最低点;高于725℃时,退火温度越高平均晶粒度越大,硬度已经趋于稳定不随退火温度的升高而变化。故高纯金属钪最佳退火工艺为725℃×30 min。经725℃×30 min退火后,锻压加工后的高纯金属钪达到完全退火态,晶粒均匀,平均晶粒尺寸为135μm,硬度值由退火前的169.5 HV2下降至退火后的129.6 HV2。

Effect of annealing temperatures on the hardness and microstructure of high-purity scandium after forging was investigated by using microhardness measurement and optical microscope observation.The results show that the average grain size of the scandium metal generally shows an upward trend as increasing of the annealing temperature under the same annealing time,and the hardness first decreases and then tends to be stable.When the annealing temperature is lower than 725℃,the recovery and recrystallization process are relatively slow and the growth of average grain size is limited,while the microhardness continues to decrease with the increase of the annealing temperature,which reaches the lowest point at 725℃.While the annealing temperature is above 725℃,the higher the annealing temperature,the larger the average grain size,and the microhardness tends to be stable with the increase of annealing temperature.The optimum annealing process for the high purity scandium metal consists of heating at 725℃for 30 min.After annealing at 725℃for 30 min,the high purity scandium metal after forging is fully annealed,the grains is uniform with a grain size of 135μm,and the hardness value decreases from 169.5 HV2 before annealing to 129.6 HV2 after annealing.