CAJ | 학술논문

通过改变定向凝固前的保温时间,研究热稳定处理对定向凝固Ti-46Al-0.5W-0.5Si(摩尔分数,％)合金组织和性能的影响.在稳定的温度梯度下(G=20 K/mm),定向凝固启动前试样分别保温5、15、30、45和60 min,然后试样以恒定的速度(ν=30 μm/s)进行定向凝固实验.测量定向凝固组织的一次枝晶间距(λ1)、二次枝晶间距(λ2)、层片间距(λL)和显微硬度(HV),并分析这些参数与热稳定处理时间(t)的关系.λ1、λ2和λL的值随着t的延长而增大,而HV则随着t的延长而减小.在定向凝固启动前,延长热稳定时间有助于获得良好的定向凝固组织,然而,过长的保温时间则会降低合金的力学性能.因此,需要优化定向凝固前的热稳定处理时间.根据实验结果,在当前实验条件下,定向凝固前热稳定处理时间选择30 min,既能够获得良好的定向凝固组织,又能保持合金较高的力学性能.
통과개변정향응고전적보온시간,연구열은정처리대정향응고Ti-46Al-0.5W-0.5Si(마이분수,％)합금조직화성능적영향.재은정적온도제도하(G=20 K/mm),정향응고계동전시양분별보온5、15、30、45화60 min,연후시양이항정적속도(ν=30 μm/s)진행정향응고실험.측량정향응고조직적일차지정간거(λ1)、이차지정간거(λ2)、층편간거(λL)화현미경도(HV),병분석저사삼수여열은정처리시간(t)적관계.λ1、λ2화λL적치수착t적연장이증대,이HV칙수착t적연장이감소.재정향응고계동전,연장열은정시간유조우획득량호적정향응고조직,연이,과장적보온시간칙회강저합금적역학성능.인차,수요우화정향응고전적열은정처리시간.근거실험결과,재당전실험조건하,정향응고전열은정처리시간선택30 min,기능구획득량호적정향응고조직,우능보지합금교고적역학성능.
Effect of thermal stabilization on the microstructure and mechanical property of directionally solidified Ti-46Al-0.5W-0.5Si (mole fraction,％) alloy was investigated.The specimens were thermal stabilized for different time (t) and directionally solidified at a constant growth rate of 30 μm/s and temperature gradient of 20 K/mm.Dependencies of the primary dendritic spacing (λ1),secondary dendritic spacing (λ2),interlamellar spacing (λL) and microhardness (HV) on holding time were determined.The values of the λ1,λ2 and λL increase with the increase oft,and the value of HV decreases with the increase oft.The increase of t is helpful to obtain a good directional solidification structure.However,it reduces the mechanical property of the directionally solidified TiAl alloy.The optimized value of t is about 30 min.