6Mn和初生Al3Sc組成。SLM成形的合金熔池組織呈魚鱗狀，熔池內(nèi)靠近熔合線附近形成了大量細(xì)小的等軸晶，平均晶粒尺寸約為0.57 μm，熔池心部則由柱狀晶組成，柱狀晶的平均寬度約為0.48 μm。棒狀A(yù)l6Mn主要沿晶界分布，少量顆粒狀的初生Al3Sc存在于晶粒內(nèi)部，這表明初生Al3Sc可以作為異質(zhì)形核質(zhì)點(diǎn)，細(xì)化α-Al基體。熱處理后，熔池內(nèi)部等軸晶尺寸及柱狀晶寬度均有所增大，組織中析出了大量細(xì)小彌散的二次Al3Sc顆粒。硬度測試結(jié)果表明，隨著時效時間的延長，各溫度條件下合金的硬度值呈先升高后降低的趨勢，相比于沉積態(tài)合金的硬度，在325 ℃、180 min時效熱處理后合金的硬度提高了30%左右，達(dá)到1813.0 MPa。;Al-Mn-Mg-Sc-Zr alloy was prepared by selective laser melting (SLM) technique. The microstructure of Al-Mn-Mg-Sc-Zr alloy before and after heat treatment was characterized by X-ray diffractometer, scanning electron microscope, energy dispersive spectrometer, and transmission electron microscope, and the hardness of the alloy was tested. Results show that the microstructure of as-deposited alloy is mainly composed of α-Al, Al6Mn, and primary Al3Sc phases. The SLMed molten pool presents the fish-scale shape, and a large number of fine equiaxed crystals are formed near the fusion line of molten pool with average grain size of about 0.57 μm. The center of the molten pool is composed of columnar crystals with average width of about 0.48 μm. The rodlike Al6Mn phase is mainly distributed along the grain boundary, and a small amount of granular primary Al3Sc phase exists inside the grain, which indicates that the primary Al3Sc can be used as heterogeneous nuclear particle to refine the α-Al matrix. After heat treatment, the size of equiaxed crystals and the width of columnar crystals in the molten pool are increased, and a large number of fine and dispersed secondary Al3Sc particles are precipitated in the structure. The hardness test results show that the hardness of the alloy is increased firstly and then decreased with prolong the aging durations at different temperatures. Compared with that of the as-deposited alloy, the hardness of the alloy after peak aging (325 °C/180 min) heat treatment increases by about 30%, reaching 1813.0 MPa."/>