摘要
为了进一步揭示增材制造对金属材料的微观组织与高温氧化性能的影响规律,本文采用光学显微镜、扫描电子显微镜、能量色散谱、电子背散射衍射和X射线衍射等方法,对比研究了轧制态与激光选区熔化(Selective Laser Melting, SLM)制备的Inconel 625合金垂直和平行于成形方向横截面(XY和XZ面)的微观结构,并探究了两种合金在900℃下的高温氧化性能。研究表明,SLM制备的合金与传统轧制合金的显微组织存在明显区别:轧制合金呈等轴晶,晶粒尺寸为(15±2.5)μm,具有更多的大角度晶界和较大的位错密度;SLM制备的合金呈多晶结构,主要由胞状晶与柱状晶组成,晶粒尺寸不均匀,其中胞状晶晶粒尺寸为0.2~2μm,位错密度较小,呈现高度织构化特征;XRD结果表明,SLM并未改变合金的物相,SLM与轧制成形Inconel 625合金由γ-Ni相组成。SLM合金的XY面和XZ面的晶粒取向存在较大差别,其中XZ面的晶粒取向为(001)。在900℃下,SLM合金的氧化速率更高,这种高氧化速率导致氧化膜致密性差,在SLM合金的亚表层区域形成空洞。轧制Inconel 625合金的抗氧化性能优于SLM合金,这主要归因于轧制合金具有更多的位错与孪晶。
The influence of additive manufacturing on the microstructure and high temperature oxidation properties of metal materials was investigated. As-rolled and selective laser melting(SLM) formed Inconel 625 alloy blocks were prepared. The microstructures of the cross-sections(perpendicular and parallel to the forming directions, namely XY plane and XZ plane) of alloys were comparatively analyzed by means of optical microscope(OM), scanning electron microscope(SEM), energy dispersion spectroscopy(EDS), electron backscatter diffraction(EBD), and X-ray diffraction(XRD). The high temperature oxidation properties of the two alloys at 900 ℃ were studied. Results show that the microstructure of the alloy prepared by SLM was obviously different from that of traditional rolled alloy. The rolled alloy presented a microstructure of equiaxed grains with grain size of(15±2.5) μm, and there were more high-angle grain boundaries and higher dislocation density. The alloy prepared by SLM presented a polycrystalline structure, which mainly consisted of cellular crystal and columnar dendrite;the grain size was uneven: the cellular crystal grain size was 0.2~2 μm, and the dislocation density was smaller with highly textured characteristics. XRD results show that SLM did not change the phase of the alloy, and both materials had the phase structure of γ-Ni phase. There was a great difference in grain orientation between XY plane and XZ plane of SLM formed alloy, and the grain orientation was(001) for XZ plane. At 900 ℃, the oxidation rate was higher for alloys prepared by SLM, which induced poor oxide scale compactness, as well as void formation in the subsurface region of alloys. The oxidation resistance of rolled Inconel 625 alloy was better than that of SLM formed alloy, which was mainly attributed to the fact that the rolled alloy had more dislocations and twins.
作者
陶明生
任延杰
黄杰
周立波
邱玮
黄伟颖
李聪
陈荐
牛焱
TAO Mingsheng;REN Yanjie;HUANG Jie;ZHOU Libo;QIU Wei;HUANG Weiying;LI Cong;CHEN Jian;NIU Yan(College of Energy and Power Engineering,Changsha University of Science&Technology,Changsha 410114,China)
出处
《材料科学与工艺》
CAS
CSCD
北大核心
2022年第4期1-10,共10页
Materials Science and Technology
基金
国家自然科学基金面上项目(52171066,52175129)
湖南省教育厅重点项目(21A0204)。
