退火对液氮轧制CrCoNi中熵合金组织与性能的影响

Effects of Annealing on Microstructure and Properties of CrCoNi Medium Entropy Alloy After Liquid Nitrogen Temperature Rolling

针对CrCoNi中熵合金具有优异的液氮性能,但其液氮轧制后塑性较差(<8%)所带来的难加工问题,以电弧熔炼铸态CrCoNi中熵合金为研究对象,在液氮(77 K)下对CrCoNi合金进行3道次轧制变形,总变形量为50%。随后,在650、700、800℃下保温30min进行退火。结果表明,CrCoNi中熵合金经过液氮轧制及随后退火,未发生物相结构改变。退火后,变形晶粒发生再结晶而细化,并产生∑3退火孪晶。随退火温度的升高,再结晶程度增加,延伸率提高。通过液氮轧制与中温短时间退火进行性能调控,可获得强度与韧性匹配的性能,并提高了热处理工艺效率。

The medium entropy alloy of CrCoNi has excellent low temperature properties,but its plasticity is poor(<8%)after liquid nitrogen temperature rolling.In this research,arc-melted cast CrCoNi entropy alloy was rolled under liquid nitrogen at 77 K.The total deformation of CrCoNi alloy was 50%after three passes rolling.Then,annealing was carried out at 650,700 and 800℃ for 30 min.The results show that after rolling and annealing,phase structure of CrCoNi medium entropy alloy does not change.After annealing,the deformed grains become finer andΣ3 annealing twins occur.With the increase in annealing temperature,the number of recrystallized grains increases and the elongation increases.It can be concluded that through the cold rolling and medium temperature annealing in a short time to control the properties the strength and toughness can be matched.And the efficiency of heat treatment process is improved.