真空烧结和氢致相变烧结制备Ti-xFe合金的组织演变过程和性能研究

Microstructure evolution and properties of Ti-xFe alloys prepared by vacuum sintering and hydrogen induced phase transformation sintering

摘要:

以HDH-Ti粉和羰基Fe粉为原料,经冷等静压成形后,分别采用真空烧结和氢致相变烧结(HSPT)制备Ti-xFe合金(x=1%、5%、10%和15wt%),对比研究了两种烧结工艺中合金的密度、物相、组织演变过程和显微硬度等性能。结果表明：HSPT合金含有较多的孔隙,密度明显低于真空烧结合金的密度。两种方法制得合金中的β相含量均随Fe含量的增加而增加,且在HSPT制备的Ti-15Fe合金出现了TiFe中间相。HSPT合金制备过程中,H对Fe元素的扩散产生了显著的抑制作用。当Fe≥5%时,脱氢后在合金的β相内部析出短棒状或针状的次生α相,使得β相组织细小。当Fe≥10%时,Fe出现了明显的富集。同时H元素导致β相向粗大化的方向发展,而且随Fe含量的增加,β相粗化越明显。HSPT合金的显微硬度高于真空烧结合金,尤其是α相的显微硬度随Fe含量的增加而线性增大。

Abstract:

With HDH-Ti powder and carbonyl Fe powder as raw materials and formed by cold isostatic pressing, Ti-xFe alloys (x=1%, 5%, 10% and 15wt%) were prepared by vacuum sintering and hydrogen induced phase transformation sintering (HSPT), respectively. The density, phase, microstructure evolution and microhardness of the alloys in the two sintering processes were compared. The results show that the HSPT alloy contains more pores and the density is significantly lower than that of the vacuum sintered alloy. The content of β phase in the two alloys increases with the increase of Fe content, and TiFe phase appears only in the Ti-15Fe alloy prepared by HSPT. During the preparation of HSPT alloy, H has a significant inhibitory effect on the diffusion of Fe. When Fe content is no less than5%, short rod-like or needle-like secondary α phase is precipitated inside the β phase of the alloy after dehydrogenation, which makes the β phase structure fine. When Fe content reaches 10% or higher, Fe appears significant enrichment. At the same time, H leads to the development of the β phase growing coarsening, and the β phase coarsening is more obvious with the increase of Fe content. The microhardness of HSPT alloy is higher than that of the vacuum sintered alloy, especially that of α phase increases linearly with the increase of Fe content.