放电等离子烧结制备9Cr-ODS钢的组织与力学性能

Microstructure and mechanical properties of 9Cr-ODS steel prepared by spark plasma sintering

采用放电等离子烧结（Spark plasma sintering,SPS）工艺制备了成分为Fe-9Cr-1.5W-0.4Mn-0.2V-0.1Ta-0.3Ti-0.3Y2O3（质量分数,%）的9Cr-ODS钢。利用扫描电镜（SEM）、透射电镜（TEM）、电子背散射衍射（EBSD）、高分辨透射电镜（HRTEM）对ODS钢的宏观烧结特征、晶粒形貌、析出相形貌等进行表征。利用万能拉伸试验机测量不同温度下样品的力学性能。结果表明：通过放电等离子体烧结工艺可以制备出具有超细晶粒的ODS钢,950℃/5 min时烧结效果最好,致密度达到97.7%。950℃/5 min烧结后样品的晶粒呈现粉末颗粒表面晶粒粗大（〉1μm）而内部晶粒细小（纳米级）的现象,样品内的析出相以高密度、纳米尺寸、弥散分布的纳米团簇为主,其分布密度可以达到5.1×10^22个/m^3,同时还发现了少量化学计量比的Y2Ti2O7。放电等离子体950℃/5 min烧结样品的常温和650℃拉伸强度分别达1040 MPa和407 MPa。

9 Cr-ODS steel with composition of Fe-9 Cr-1. 5 W-0. 4 Mn-0. 2 V-0. 1 Ta-0. 3 Ti-0. 3 Y2 O3（ mass fraction,%） was prepared by spark plasma sintering（ SPS） process. Microstructure,macroscopic sintering characteristics,grain morphology and precipitate phase morphology of the 9 Cr-ODS steel were studied by means of scanning electron microscopy（ SEM）,transmission electron microscopy（ TEM）,electron backscattering diffraction（ EBSD） technique,and high resolution transmission electron microscopy（ HRTEM）. The mechanical properties of the 9 Cr-ODS steel at different temperatures were tested by universal tensile testing machine. The results show that the 9 Cr-ODS steel with ultrafine grain can be prepared by SPS process. The relative density of the 9 Cr-ODS steel prepared by sintering at950 ℃ for 5 min is the highest,up to 97. 7%. The grain size of the steel prepared by sintering at 950 ℃ for 5 min is large（ 1 μm）on the surface of the powder particle and the inner grain is fine（ nanometer level）. The precipitate phase in the steel is featured with high density,nanometer size and good dispersion,and its distribution density reaches 5. 1 × 10^22/m^3. A small amount of Y2 Ti2 O7 precipitate phase is also found. The tensile strength of the steel prepared by spark plasma sintering at 950 ℃ for 5 min at room temperature and650 ℃ reaches 1040 MPa and 407 MPa,respectively.