Effect of laser linear energy density on microstructure evolution and mechanical properties of 75W-FeCoNiCr alloy
A new type of 75W-FeCoNiCr alloy was prepared by laser directed energy deposition(L-DED)using FeCoNiCr high entropy alloy as the bonding phase.The effects of laser line energy density on the phase composition,relative density,microstructure and mechanical properties of the alloy were discussed.The results show that in the range of linear energy density from 157.14-325.00 J/mm,the alloy phase composition has no obvious change at different linear energy densities,and all of them are composed of BCC-W phase,TCP intermetallic compound precipitation phase Co7W6 and FCC-FeCoNiCr bonding phase.With the increase of linear energy density,the constitutional supercooling increases,the growth rate of the precipitated phase increases,its shape changes from plate/cell to dendrite,and its size increases from 1 μm to about 8 μm.With the increase of linear energy density,the density,microhardness and compressive strength of the alloy increase first and then decrease.When the linear energy density is 166.67 J/mm,the precipitated phase is mainly uniform cellular structure.At this time,the density,microhardness and compressive strength of the alloy reach the highest values,which are 98.4％,656 MPa and 2 261 MPa,respectively.
tungsten alloyshigh-entropy binder phaselaser directed energy depositionline energy densitymelt pool morphology
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