【摘要】 采用熔体旋转冷却法制备了Al-Mg-Si和Al-Mg-Si-Mn合金带材,并将带材预制成坯在500℃下热挤压成致密化棒材,之后进行固溶+人工时效处理。结果表明,通过甩带法制备的带材组织均匀且晶粒细小,在Al-Mg-Si合金中添加0.2%的Mn的热挤压棒材的抗拉强度和屈服强度分别为227MPa和160MPa,相比于Al-Mg-Si热挤压棒材,其力学性能明显提高,同时伸长率保持在20%以上。添加Mn元素形成了新的MnAl₆第二相,钉扎在晶界上,阻碍挤压过程亚晶界的迁移。此外,Mn能代替β-AlFeSi相中的部分Fe构成β-Al（FeMn）Si相,使β相由长针状向团状α-Al₈（FeMn）₂Si相转变,降低Fe相的有害作用。在T6热处理中,Al-Mg-Si-Mn合金中形成的含Mn弥散相能够抑制小角度晶界向大角度晶界的转变。此外,合金中晶粒均产生新的取向,织构发生一定的偏转,但AlMg-Si-Mn合金中仍保留着<111>丝织构,这可能是在再结晶过程中,含Mn弥散相抑制原始变形织构中的亚晶界迁移,故再结晶晶粒生长受到抑制,相比于Al-Mg-Si合金而言,更倾向于在热处理条件下保持原有取向。更多还原

【Abstract】 The Al-Mg-Si and Al-Mg-Si-Mn alloy strips with fine grains and homogeneous microstructure were prepared by the single roll melt rotating process,and the strip was prefabricated and hot extruded into densified bar at 500℃,and then it was treated by solid solution and artificial ageing treatment.The results reveal that the strip produced by the melt-spun method presents uniform structure with fine grain,and the tensile strength and yield strength of Al-Mg-Si-0.2Si alloy reach 227 MPa and 160 MPa,greatly increased compared with those of the AlMg-Si alloy,respectively,while the elongation remains above 20%.The addition of Mn can promote the formation of a new second phase MnAl₆,which is nailed to the grain boundary,hindering the migration of subcrystals during the extrusion process,and thus inhibiting the dynamic recrystallization.In addition,certain amount of Fe in β-AlFeSi phases are replaced by Mn to form β-Al（FeMn）Si,resulting in the long-needle shapeβphase transforming into lumpyα-Al₈（FeMn）₂Si phase,relieving the harmful effects of Fe.At T6 state,Mn-containing dispersed phase formed in Al-Mg-Si-Mn alloy can inhibit the transition from small angle grain boundary to large angle grain boundary.In addition,new grain orientation and texture deflection occurr in both alloys,however <111> texture still is remained in Al-Mg-Si-Mn alloy,which may be attributed to the inhibition of sub-grain boundary migration by Mn-containing dispersed phase in original deformed texture during recrystallization,hindering the growth of recrystallized grains.Compared with Al-Mg-Si alloy,the Al-Mg-Si-Mn alloy is preferred to maintain its original orientation under heat treatment.更多还原