9Cr-ODS钢的烧结收缩动力学曲线特征

Shrinkage kinetics feature of 9Cr-ODS steels during sintering

以N2气雾化的9CrW铁基合金粉末和纳米Y2O3粉末为原料,采用放电等离子烧结(SPS)工艺制备9Cr-ODS钢。通过SPS温度和位移测量单元研究烧结压力、升温速率和Y2O3含量对烧结过程中9Cr-ODS钢烧结收缩动力学曲线的影响,并对其显微组织和力学性能进行观察和测试。结果表明,增加烧结压力能够使9CrW铁基合金粉末在较低的温度下完成烧结收缩过程。升温速率增大时,收缩曲线向高温区移动,剧烈收缩温度、最大收缩速率和密度均有所提高。Y2O3的加入可阻碍收缩致密化过程,导致曲线的最大收缩速率降低,并且力学性能测试结果表明Y2O3的加入可提高材料的拉伸性能,通过添加质量分数为0.35%的Y2O3可使得材料的抗拉强度和屈服强度分别提高到1 653 MPa和1 405 MPa。

9Cr oxide-dispersion-strengthened（ODS） steels were prepared by the 9CrW iron-based powders atomized in nitrogen gas with nanometer Y2O3 powders consolidated by spark plasma sintering（SPS）.Effects of sintering pressure,heating rate and Y2O3 content on the shrinkage kinetic curves were investigated by SPS temperature and displace measurement;moreover,microstructure and mechanical properties of 9Cr-ODS steels were also characterized and measured.The results show that the shrinkage densification of 9CrW iron-based alloyed powders can complete at low temperature with increasing sintering pressure.Increasing heating rate,the shrinkage curves translate to high temperature region;in addition,the sharp shrinkage temperature,maximum shrinkage rate and density increase.Shrinkage densification is hindered by adding Y2O3 powders,which makes the maximum shrinkage rate decrease.Electronic tensile test shows that tensile properties can be improved by adding Y2O3.The ultimate tensile strength and yield strength increase to 1 653 MPa and 1 405 MPa when adding 0.35%（mass fraction） Y2O3.