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Sintering of titanium in argon and vacuum: Pore evolution and mechanical properties
International Journal of Refractory Metals & Hard Materials ( IF 3.6 ) Pub Date : 2020-03-05 , DOI: 10.1016/j.ijrmhm.2020.105226
S.D. Luo , B. Liu , J. Tian , M. Qian

Reducing porosity can help to improve the mechanical properties of an as-sintered material. An alternative is, however, to tailor the size, distribution and morphology of the residual pores without having to further reduce porosity. This study investigates the sintering of commercially pure titanium (CP Ti) in a flowing argon (Ar) atmosphere and compares the results with sintering in a vacuum of 10−2 Pa. The CP Ti sintered in Ar at 1300 °C for 2–3 h exhibited a marginally lower density but clearly better tensile ductility than Ti sintered in vacuum. The sensitivity of tensile ductility to residual pores was analyzed. Samples sintered in Ar exhibited much lower sensitivity than those sintered in vacuum. The superior ductility arises from the beneficial effect of sintering in Ar, which resulted in a greater number of but smaller residual pores with lower pore aspect ratios and finer matrix grains due to the grain-growth inhibiting role of the residual pores. The reason is attributed to the entrapped Ar in the closed pores during sintering, which is insoluble in Ti at the sintering temperature. The ever-increasing internal pore pressure prevents further pore shrinkage after reaching a critical size. The final pore size range is predicted and compared with experimental observations. Sintering of titanium in Ar is advantageous over sintering in vacuum in terms of both pore size distribution and pore morphology within a reasonable isothermal sintering period (e.g., 3 h at 1300 °C). Therefore, it can be more attractive for non-fatigue critical applications than sintering in vacuum.



中文翻译:

氩气和真空中钛的烧结:孔的演变和力学性能

降低孔隙率可以帮助改善烧结材料的机械性能。但是,另一种方法是调整残留孔的大小,分布和形态,而不必进一步降低孔隙率。这项研究研究了在流动的氩(Ar)气氛中烧结商业纯钛(CP Ti)的结果,并将结果与​​在10 -2真空下的烧结结果进行了比较 Pa。在1300°C的Ar中烧结2–3 h的CP Ti的密度略低,但拉伸延展性明显优于在真空中烧结的Ti。分析了拉伸延性对残余孔的敏感性。在Ar中烧结的样品比在真空中烧结的样品显示出低得多的灵敏度。优异的延展性来自于Ar烧结的有益作用,由于残余孔的晶粒长大抑制作用,它导致了更多但较小的残余孔,孔纵横比较低,且基体晶粒更细。原因归因于在烧结期间在封闭的孔中截留的Ar,其在烧结温度下不溶于Ti。不断增加的内部孔隙压力会在达到临界尺寸后阻止进一步的孔隙收缩。预测最终的孔径范围,并将其与实验观察结果进行比较。就在合理的等温烧结时间段(例如,在1300°C下3 h)内的孔径分布和孔形貌而言,在Ar中钛的烧结优于真空烧结。因此,对于非疲劳关键应用而言,它比在真空中烧结更具吸引力。

更新日期:2020-03-05
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