The main defects of laser spot welding of aluminum are crater, hot crack and porosity which created by oxide film and keyhole instability,.
焊点中存在的主要缺陷是气孔，表面下塌，热裂纹，其中气孔主要为氧化膜气孔和匙孔不稳定形成的气孔。
The fabrication of thin oxide films has become a hot spot of research in physics of condensed matter.
氧化物薄膜的制备已经成为凝聚态物理学的一个研究热点。
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