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研究了原位烧结法制备TiAl基超细晶/纳米晶合金。首先,通过球磨方式细化TiH2,Al,Si和Nb粉,然后将球磨后粉末进行放电等离子烧结。利用X射线衍射仪、扫描电镜和透射电镜分析球磨粉末及其烧结块体的特性,利用差热分析仪测试高温抗氧化性。试验结果显示,球磨过程中产生了非晶、Ti3Al纳米晶和TiH2的分解产物,球磨后粉末经高温烧结时,这些细小粉末迅速地转变成TiAl和Ti3Al相,TiAl相的晶粒尺寸为500 nm~1μm,Ti3Al相为几个纳米,这种超细烧结组织在1000℃下非常稳定,而且具有良好的抗氧化性。
The in-situ sintering method was used to prepare TiAl-based ultrafine crystal / nanocrystalline alloy. First, the TiH2, Al, Si and Nb powders are refined by ball milling, and then the ball milled powder is subjected to spark plasma sintering. The properties of the ball mill powder and the sintered block were analyzed by X-ray diffraction, scanning electron microscopy and transmission electron microscopy. The high temperature oxidation resistance was tested by differential thermal analyzer. The results showed that during the milling process, amorphous, Ti3Al nanocrystals and TiH2 decomposition products were produced. When the powders were sintered at high temperature, the powders were rapidly transformed into TiAl and Ti3Al phases. The grain size of TiAl phase was 500 nm ~ 1μm, Ti3Al phase is a few nanometers, this ultrafine sintered structure is very stable at 1000 ℃, and has good oxidation resistance.