大應變熱軋噴射成形高鎂鋁合金的微觀結構及力學性能大應變熱軋噴射成形高鎂鋁合金的微觀結構及力學性能Microstructures and mechanical properties of spray-forming high magnesium aluminum alloy during large strain hot rolling 基于常規熱軋工藝對噴射成形高鎂鋁合金擠壓坯進行單道次大應變熱軋變形，采用透射電鏡(TEM)、掃描電鏡電子背散射成像技術(EBSD)和X衍射(XRD)方法來分析合金微觀結構，并對比研究合金的力學性能。結果表明：噴射成形高鎂鋁合金在熱軋變形過程中，隨著變形程度的增大，位錯密度顯著增大，位錯胞、非平衡小角度晶界(LAGB)及亞晶顯著增多；當熱軋變形80%時，高位錯密度晶粒中的小角度晶界轉變為大角度晶界(HAGB)，亞微米級動態再結晶晶粒大量形成，晶粒組織顯著細化，合金的室溫拉伸強度和伸長率分別為619 MPa和19.8%。噴射成形高鎂鋁合金大應變熱軋變形過程中的主要強化機制是細晶強化、位錯強化和固溶強化，對變形80%合金屈服強度的貢獻值分別為120 MPa、208 MPa和158 MPa，共占總強度值的94.4%。 The extrusion preform of the spray-forming Al alloy with high Mg content is hot rolled by 1-pass large deformation based on the conventional rolling technology. By transmission electron microscopy (TEM), electron backscatter diffractometry (EBSD) and X-ray diffractometry (XRD), the microstructure and mechanical properties of the alloy were investigated. The results indicate that the density of dislocation and the amount of dislocation cells, non-equilibrium low angle grain boundaries (LAGB) and subgrains increase with the increase of deformation during the hot rolling process. At the hot rolling deformation of 80%, the LAGB among the grains with high dislocation density transforms into high angle grain boundaries (HAGB), a large number of submicron dynamic recrystallization grains form, and the grains are significantly refined. The tensile strength and elongation at the room temperature of the alloy reach 619 MPa and 19.8%, respectively. The main strengthening mechanisms of the spray-forming Al alloy with high Mg content during the large hot rolling process are fine grain strengthening, dislocation strengthening and solid solution strengthening, the contribution of which to the yield strength of the alloy with 80% deformation are 120, 208 and 158 MPa, respectively, reaching 94.4% of the total strength.
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