退火对液氮轧制CrCoNi中熵合金组织与性能的影响

Effect of annealing on microstructure and properties of medium entropy alloy CrCoNi after liquid nitrogen temperature rolling

摘要:

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,本文以电弧熔炼铸态CrCoNi中熵合金为研究对象,在液氮(77K)下对CrCoNi合金进行了3道次轧制变形,总变形量为50 %。随后,采用650 ℃、700 ℃、800 ℃三种温度,保温时间为30 min下进行退火。实验数据表明：CrCoNi中熵合金经过轧制及退火后,未发生物相结构改变,退火后,变形晶粒发生再结晶细化,并产生∑3退火孪晶,随退火温度升高,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。

关键词:液氮轧制，中熵合金，组织，断口形貌，硬度

Abstract:

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 melting of casted CrCoNi entropy alloy as the research sample, rolling deformation of CrCoNi alloy at low temperature (77K) for three passes, the total deformation was 50%. Then, annealing was carried out at 650 ℃, 700 ℃ and 800 ℃ for 30 minutes. Experimental data show that: CrCoNi medium entropy alloy after rolling and annealing, not material phase structure changed, after annealing. Because of recrystallization, deformation grains become smaller, and generated ∑3 annealing twin in organization. As the annealing temperature increased, the number of recrystallized grains increased, the elongation increased. It can be concluded that through the cold rolling and medium temperature annealing in short time performance controlling, matching the performance of the strength and toughness can be obtained, The efficiency of heat treatment process was improved.

Key words:liquid;nitrogen temperature;rolling, medium;entropy alloy, Microstructure, fracture;morphology, hardness