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球磨工艺对球磨粉末及其烧结组织的微观结构和形态都有重要的影响。本实验采用低能和高能球磨2种方式对Ti-7Al-0.2B(质量分数,%)合金粉末进行球磨,研究球磨过程中粉末组织和形态的变化,并将球磨后的粉末进行热压烧结,研究不同球磨方式对烧结组织中原位合成TiB增强相形态的影响。研究结果表明:低能球磨过程中,粉末颗粒间有机械合金化发生,其烧结组织中生成的TiB为细长态,在基体中分布均匀,没有联结的粗晶或成簇生长现象。对于高能球磨,粉末颗粒细化效果明显,颗粒平均尺寸降至1μm,球磨过程中除了机械合金化还形成了Ti(Al)过饱和固溶体,并在球磨后期形成了非晶结构。经高能球磨的粉末烧结后,组织中生成了均匀分布的纳米级TiB晶须。
Ball milling process on the ball milling powder and sintered microstructure and morphology have a significant impact. In this experiment, Ti-7Al-0.2B (mass fraction,%) alloy powders were ball-milled by low energy and high-energy ball milling. The microstructure and morphology of the powders during ball milling were studied. The effects of different ball milling methods on the morphology of in situ synthesized TiB reinforcing phase in sintered microstructure were studied. The results show that during the process of low energy ball milling, mechanical alloying occurs among the powder particles, and the TiB formed in the sintered microstructure is elongated, distributed uniformly in the matrix, and there is no coherent coarse grain or cluster growth phenomenon. For the high-energy ball milling, the grain refinement effect of the powder is obvious, the average size of the particles is reduced to 1μm, Ti (Al) supersaturated solid solution is formed in addition to the mechanical alloying during ball milling, and the amorphous structure is formed at the later stage of ball milling. After the high-energy ball milling powder sintering, the organization generated uniformly distributed nano-TiB whiskers.