Abstract
The properties of modified conventional wrought aluminum alloys cannot be significantly enhanced by normal post-heat treatment in that the fine-grained strengthening,arising from high cooling rate in SLM,is underutilized.In this work,compared with the normal T6 heat treatment,a novel simple direct ag-ing regime was proposed to maintain the grain-boundary strengthening and to utilize the precipitation strengthening of secondary Al3Zr.It was found that a heterogeneous grain structure,which consisted of ultrafine equiaxed(～0.82 μm)and columnar(～1.80 μm)grains at the bottom and top of molten pool,respectively,was formed in the SLM processed sample.After direct aging(DA),the ultrafine grains were maintained and a mass of spherical coherent L12-Al3Zr particles with a mean radius of approximately 1.15 nm was precipitated.In contrast,after solution treatment and aging(STA),a significant grain coars-ening occurred in the equiaxed grain region.Meanwhile,the coarsening L12-Al3Zr particles,nano-sized S'phases and GPB zones were detected in the STA sample.This subsequently induced that the yield strength of the DA sample(～435 MPa)was higher than that of the STA sample(～402 MPa)owing to the grain boundary strengthening and precipitation strengthening.Both the STA and DA samples exhibited a higher strength than that of the other SLMed Al-Cu-Mg series alloys;this was comparable to that of the wrought AA2024-T6 alloy(～393 MPa).Both the STA and DA samples exhibited a higher strength than that of the other SLMed Al-Cu-Mg series alloys;this was comparable to that of the wrought AA2024-T6 alloy(～393 MPa).
基金项目
National Key Research and Development Program of China(2018YFB1106300)
国家自然科学基金(51604227)
Fundamental Research Funds for the Central Universities(31020180QD130)
NETL
NSTL
维普
万方数据