(1. 北京科技大學(xué) 新金屬材料國家重點實驗室，北京 100083；
2. 機械科學(xué)研究總院 先進制造技術(shù)研究中心，北京 100083；
3. 北京科技大學(xué) 材料科學(xué)與工程學(xué)院，北京 100083)
摘 要: 在保護氣氛中采用噴射成形技術(shù)制備AZ91和AZ91+2.0%Si鎂合金，采用OM、SEM、XRD及TEM等技術(shù)分別對合金的微觀組織進行觀察和分析。結(jié)果表明：與相同成分的鑄造鎂合金相比，噴射成形技術(shù)顯著細化合金組織；噴射成形沉積態(tài)AZ91鎂合金具有均勻、細小的等軸晶組織，平均晶粒尺寸約為17 μm，離異共晶β-Mg17Al12相在晶界的偏析被有效改善；對于噴射成形AZ91+2.0%Si鎂合金，噴射成形過程中高的冷卻速度抑制了Mg2Si相的長大，細小的Mg2Si相呈現(xiàn)為近球形或多邊形態(tài)，與基體結(jié)合良好且彌散分布，并可以作為α-Mg異質(zhì)形核核心，使合金組織得到充分細化。
關(guān)鍵字: AZ91鎂合金；噴射成形技術(shù)；Mg2Si；晶粒細化
（1. State Key Laboratory for Advanced Metals and Materials, University of Science and Technology Beijing,
Beijing 100083, China;
2. Advanced Manufacture Technology Center, China Academy of Machinery Science & Technology,
Beijing 100083, China;
3. School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing 100083, China）
Abstract: AZ91 and AZ91+2.0%Si Mg alloys were prepared by spray forming technology in protecting atmosphere. The microstructures were studied by optical microscopy (OM), scanning electron microscopy (SEM), X-ray diffractometry (XRD) and transmission electron microscopy (TEM). The results show that the microstructures of spray formed magnesium alloys are fine-grained compared with as-cast ones with the same compositions. The microstructure of as-sprayed AZ91 Mg alloy is uniform, fine and equi-axed. The average size of particles is about 17 μm, and the nonuniform precipitation of divorced eutectic β-Mg17Al12 is effectively improved. In the microstructure of as-sprayed AZ91+2.0%Si, the high cooling speed during spray forming process restrains the growth of Mg2Si. Mg2Si existing in the fine grains, presents polygonal or near round shape, which uniformly distributes and can be the heterogeneous core of α-Mg, so the spray formed AZ91 Mg alloy is sufficiently refined by Si added.
Key words: AZ91 Mg alloy; spray forming technology; Mg2Si; grain refinement
