High strength and ductility on Ni6W2Cr4Fe8Ti1 high entropy alloys by selective laser melting

Abstract

High entropy alloys (HEAs) have a good application potential in the preparation of high temperature service parts with complex shapes in additive manufacturing. Powder bed fusion (PBF) is a prominent type of additive manufacturing process that utilizes the thermal energy to bind powder materials together to build up plastic or metallic parts. However, the traditional gas atomization method (GA) often produce alloy powder (containing refractory element) with uneven composition, affecting the quality and performance of specimens. That is why innovative or opposite classical production powder methods are in demand for the PBF. It is worth noting that mechanical alloying technology overcomes the limitation of high temperature alloying of HEA containing refractory elements and realizes solid alloying of insoluble elements. In this paper, high entropy alloy Ni6W2Cr4Fe8Ti1 containing refractory elements is designed by means of composition control. Its spherical powders with uniform composition were successfully prepared by the new mechanical alloying - high temperature remelting spheroidization dual process (DP) method. The treated powder composition is evenly distributed with particle sizes ranging from 15 to 28 μm. And the spheroidization rate has exceeded 98.23% at 1943 K. The sample value of YS and UTS on Ni6W2Cr4Fe8Ti1 (DP-SLM) has increased by 35.7%, 45.5% and 27.3%, respectively in additive manufacturing, compared to GA-SLM. The ability to produce refractory HEA through DP method will make it possible to manufacture complex geometry shapes at a reasonable cost. It offers theoretical guidance to manufacture fine grain materials with high strength and ductility of new HEA components.

Keywords

• Powder bed fusion
• Ni6W2Cr4Fe8Ti1
• Solute homogenization
• Mechanical alloying
• Mechanical properties