Laser Metal Deposition of Al-7050/Al50Mg50 Gradient Material

Laser metal-deposited Al 7050 alloy exhibits reduced Mg and Zn content compared to parent composition due to substantial evaporation. This paper presents a technique to investigate various Al 7xxx alloy compositions in a single coupon. In this investigation, a gradient sample of Al 7050/Al50Mg50 was fabricated layer-by-layer by the gradual addition of Al50Mg50 alloy with the Al 7050 powder. A correlation was developed between Mg content in powder feed and the resulting gradient deposit. Microscopy investigation revealed that there were no major defects in gradient sample such as porosity or lack of fusion. Formation of strengthening precipitates primarily Al₃Mg₂ and MgZn₂ was escalated with the gradual addition of Mg from bottom to the top layer of the Al 7050/Al50Mg50 gradient material. The EDS investigation showed that with the addition of more Mg, respective loss increases in the subsequent layer as compared to a loss of Mg in the previous layer. Microhardness gradually increased from 94 to 154 HV corresponding to Mg content of 2.8 to 23 wt pct in the first and last layer, respectively. This technique is very useful to develop new alloys by studying various compositions in one sample saving time and effort.