Full
Outline
Selective laser melting （SLM） technology， with its unique solidification characteristics， can overcome the issue of coarse grain size in conventionally cast alloys. To achieve grain refinement and improve the mechanical properties of Cu-Al-Ni alloy prepared by SLM， the effects of key process parameters， including laser power and scanning speed， on the microstructure and mechanical properties perpendicular to and along the building direction are studied. The results show that fully overlapping melt tracks are present perpendicular to the building direction， in contrast， parallel to the building direction， it shows columnar grains that have grown epitaxially layer by layer. Both directions primarily consist of lath martensite. With increasing scanning speed at constant laser power， or with slightly decreasing laser power at fixed scanning speed， the melt tracks become narrower， and both the grains and martensite are refined. At a laser power of 280 W and a scanning speed of 850 mm/s， the resulting alloy exhibits the narrowest melt tracks， the finest grain size and martensitic structure， and the best mechanical properties. The hardness and compression strength measured along the building direction reach 251.2HV and 1465 MPa， respectively， while these perpendicular to the building direction reach 245.7HV and 1189 MPa， respectively. The refinement of grains and martensite is attributed to the high cooling rate inherent to SLM， and the improvement of mechanical properties is mainly due to grain refinement strengthening. The fine columnar grains， dense martensite and presence of twinning along the building direction result in higher interface density， which provides stronger resistance to dislocation slip， thereby leading to superior mechanical properties.
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| 科 Family | 属数 Number of genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) | 属 Genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) |
|---|---|---|---|---|---|---|
| 鹅膏菌科Amanitaceae | 2 | 11 | 5.26 | 鹅膏菌属 Amanita | 10 | 4.78 |
| 小菇科 Mycenaceae | 2 | 12 | 5.74 | 丝盖伞属 Inocybe | 5 | 2.39 |
| 多孔菌科 Polyporaceae | 8 | 14 | 6.70 | 蜡蘑属 Laccaria | 5 | 2.39 |
| 红菇科 Russulaceae | 3 | 23 | 11.00 | 小皮伞属 Marasmius | 6 | 2.87 |
| 小菇属 Mycena | 11 | 5.26 | ||||
| 光柄菇属 Pluteus | 5 | 2.39 | ||||
| 红菇属 Russula | 17 | 8.13 | ||||
| 栓菌属 Trametes | 5 | 2.39 |
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