Cold Compaction of Ball-Milled Nanograin Iron Alloys

摘要

Cold consolidation of ball-milled powder is often unsuccessful because theultrafine grain size and the worked condition of the powder particles make them extremely hard. Couple this with the typically large particle size of ball-milled powder and it is clear why compacts of these materials contain large porosity. A dynamic cold consolidation technique is presented that can produce high desity, high hardness compacts from ball-milled nanograined powders. This method of cold compaction of various iron alloy powders involved drop-weight upsetting of cold isostatically pressed cylinders. The resulting compacts are characterized by optical and scanning electron microscopy, microhardness, and density measurements. For comparison, results of static, cold compaction tests up to 2.5 GPa are also reported on the same materials.