退火温度对铝青铜微观组织及硬度的影响

Effect of annealing temperature on microstructure and hardness of aluminum bronze

利用光学显微镜、扫描电镜、XRD和硬度计等分析了Cu-Al-Ni合金在冷轧与退火过程中微观组织结构及硬度的变化规律,研究了合金在不同退火温度条件下的软化行为。结果表明,当采用950℃保温淬火工艺后,Cu-Al-Ni合金主要由面心立方结构的α相与体心立方结构的β相组成,分布于晶界处的β相对合金硬度的影响作用小。由于位错强化作用的显著增强,合金在冷轧后硬度明显升高,达到270 HV0.5。冷轧态Cu-Al-Ni合金在400℃以上温度退火后会发生明显软化现象,软化的主要原因是再结晶反应所引起的位错密度下降。Cu-Al-Ni合金的再结晶温度在300℃以上,高于纯铜的再结晶温度,这表明Ni、Al元素的添加有利于提高纯铜再结晶温度,并能改善其高温抗软化性能。

The evolution of microstructure and hardness of the Cu-Al-Ni alloy during cold-rolling and annealing were investigated by using optical microscopy,scanning electron microscopy,XRD and Vickers hardness tester.The effect of annealing temperature on annealing softening of the Cu-Al-Ni alloy was analyzed.The results show that the microstructure of Cu-Al-Ni alloy after water quenching at 950℃consists ofαphase matrix with fcc structure andβphase with bcc structure.Theβdistributed at grain boundary has small effect on hardness.The hardness significantly increases to 270 HV0.5 in the alloy after cold rolling due to the increase of dislocation strengthening effect.An obvious softening occurs in the cold-rolled Cu-Al-Ni alloy after annealing above 400℃,which is attributed to the decrease in dislocations resulted from the recrystallization process.In addition,the recrystallization temperature of the Cu-Al-Ni alloy is above 300℃,which is higher than that of pure copper.It is indicated that the addition of Ni and Al could significantly increase the recrystallization temperature and improve the softening resistance.