Effect of hatch spacing on the characteristics of LPBF 2195 Al-Li alloy

Abstract

Focusing on the manufacturing challenges associated with the formation of high-strength Aluminum-lithium (Al-Li) alloys, this study explores the laser powder bed fusion (LPBF) additive manufacturing method. The influence of hatch spacing on the characteristics of 2195 Al-Li alloy fabricated by LPBF is investigated. The findings suggest that variations in hatch spacing affect the overlap between "layer-to-layer" and "channel-to-channel", resulting in a maximum relative density of 99.06% and microhardness of 130.0 HV, respectively. The grain morphology exhibits epitaxial growth of columnar grains along the maximum temperature gradient. The crystalline phases, such as T2 (Al6CuLi3) and θ′/Ω (Al2Cu), are widely dispersed within the α-Al matrix, where the formation of Mg-Ag atomic clusters promotes the nucleation of the Ω phase. The 2195 specimen exhibits an ultimate tensile strength (UTS) of 295.03 ± 5.77 MPa and an elongation of 5.01 ± 0.13%. The hatch spacing significantly affects the forming quality, while metallurgical defects, fine grain strengthening, dislocation strengthening, and secondary phase strengthening collectively determine the mechanical properties of the 2195 Al-Li alloy.