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不同状态Mg-9Sr中间合金对AZ31镁合金铸态组织的影响 总被引:3,自引:0,他引:3
研究Mg-9Sr中间合金及其处理工艺对AZ31镁合金铸态组织的影响。结果表明:在AZ31镁合金中加入不同状态的Mg-9Sr中间合金(常规铸态、快速凝固态、固溶态和轧制态)对AZ31镁合金均有很好的晶粒细化效果,其中轧制态Mg-9Sr中间合金的细化效果最好,其次依次为固溶态、常规铸态和快速凝态Mg-9Sr中间合金。在Sr加入量0.1%和熔体保温时间80 min条件下,轧制态Mg-9Sr中间合金可使AZ31镁合金获得62 μm的最小平均晶粒尺寸。 相似文献
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为了改善铸态AZ80镁合金组织和性能,对均匀化处理的铸态AZ80镁合金进行了多向锻造试验,并采用金相分析、EBSD(电子背散射衍射)分析和拉伸试验等方法,进行了显微组织和力学性能的测试与分析.结果表明:与锻造前相比,多向锻造后的AZ80镁合金的平均晶粒尺寸减小了约76 μm、抗拉强度增加了66 MPa、屈服强度增加了7... 相似文献
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对半连续铸造和热挤压态AZ80镁合金进行半固态等温处理,研究了其微观组织的演变规律和α-Mg晶粒尺寸及形状系数与工艺参数的定量关系。结果表明,相同参数条件下,挤压AZ80镁合金经半固态等温处理后,α-Mg晶粒更圆整,晶粒尺寸分布更均匀;其α-Mg晶内液相出现机制以溶质元素富集和高能储备导致晶内局部优先熔化为主;而半连续铸造AZ80镁合金半固态等温处理过程中,α-Mg晶内液相出现机制以枝晶臂合并导致液相进入晶内为主。挤压AZ80镁合金经不同参数的半固态等温处理后,α-Mg晶粒尺寸均符合高斯分布;其较佳的半固态处理工艺参数为570℃保温20min,此时固、液相的相对分布更均匀,α-Mg晶粒平均形状系数为0.86,且多集中于高系数区。 相似文献
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采用不同的比压对AZ80Ti建筑用新型镁合金进行了液态模锻,并进行了显微组织和力学性能的测试与分析。结果表明:随比压从100 MPa增大至180 MPa,AZ80镁合金液态模锻件强度不断增大,伸长率减小,平均晶粒尺寸减小。与100 MPa比压相比,采用140 MPa比压成形的AZ80Ti镁合金试样的平均晶粒尺寸减小了59.13%,抗拉强度和屈服强度分别增大了42、41 MPa。AZ80Ti镁合金液态模锻的合理比压为140 MPa。 相似文献
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采用不同的工艺参数对AZ80镁合金进行了挤锻复合成形,研究了挤压温度、锻压温度对合金显微组织和冲击性能的影响。试验结果表明:随挤压温度、锻压温度增加,AZ80镁合金的平均晶粒尺寸均先减小后增大,冲击韧度均先增大后减小。当挤压温度和锻压温度均为390℃时,AZ80镁合金的平均晶粒尺寸最小,晶粒得到显著细化,冲击韧度最大,韧性最佳,冲击性能最好。挤压温度和锻压温度的升高能够激活和协调镁合金的棱柱滑移系,减小变形的阻力,进而提升镁合金内部组织的塑性变形。挤锻复合成形有利于AZ80镁合金的塑性变形,晶粒的细化和均匀化分布使得裂纹难以产生,而且第二相的分布状态也使得裂纹难以蔓延,因此经挤压后的镁合金韧性较佳。当挤压温度或锻压温度继续上升至420℃后,镁合金内部的强化相晶粒反而增大,冲击韧度变小,冲击性能下降。 相似文献
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研究了变形、时效对AZ80镁合金组织性能的影响.铸态AZ80镁合金经470℃×8h固溶处理,然后在400℃条件下进行不同变形量的热轧变形,变形后的部分镁合金进行170℃×16 h时效处理.结果表明,随着变形量的增加晶粒得到细化,当变形量达到80%时,晶粒尺寸由铸态的105 μ.m细化到3 μm,此时抗拉强度达到282.49 MPa;合金的伸长率先增加后减小,变形量为50%时伸长率达到最大,为24.21%;屈服强度先降低后增加. 相似文献
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Amanda Levinson Raja K. Mishra Roger D. Doherty Surya R. Kalidindi 《Acta Materialia》2013,61(16):5966-5978
The microstructure evolution during isothermal static annealing of magnesium alloy AZ31 was investigated to critically evaluate the contribution of extension and contraction twins to the recrystallized microstructure after room temperature deformation, and to establish the potential of these twins to alter the recrystallized texture. Contraction twins were observed to be potent sites for recrystallized nuclei having many favorable new orientations, while extension twins were not effective nucleation sites for recrystallization. Although recrystallization nucleated preferentially inside the contraction twins, producing a distribution of new orientations (far from the undesirable starting c-axis fiber texture), these new grains did not significantly influence the final texture. This was attributed to four factors: (1) unusually extensive recovery before the onset of recrystallization after c-axis compression in most grains; (2) incomplete recrystallization within grains most closely aligned with the starting fiber texture; (3) sluggish growth of grains nucleated in the compression twins; (4) grain boundaries becoming an active site for recrystallized nuclei with a majority containing orientations from the starting texture. 相似文献
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Microstructure and microtexture evolution during static annealing of a hot-extruded AZ21 magnesium alloy was studied. Apart from fine recrystallized equiaxed grains and large elongated deformed grains, a new third kind of abnormal grains that are stacked one after the other in a row parallel to the extrusion direction were observed. The crystallographic misorientation inside these grains was similar to that of the fine recrystallized grains. The large elongated grains exhibited significant in-grain misorientation. A self-consistent mechanistic model was developed to describe the formation of these grain morphologies during dynamic recrystallization (DRX). The texture of pre-extruded material, although lost in DRX, leaves a unique signature which manifests itself in the form of these grain morphologies. The origin of abnormal stacked grains was associated with slow nucleation in pre-extruded grains of a certain orientation. Further annealing resulted in large secondary recrystallized grains with occasional extension twins. 相似文献
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脉冲电流轧制对AZ31镁合金微观组织与力学性能的影响 总被引:1,自引:0,他引:1
对比研究脉冲电流轧制工艺与温轧工艺对AZ31镁合金板材的力学性能、织构、微观组织与沉淀相等方面的影响。结果表明:脉冲电流具有促进冷轧AZ31镁合金低温再结晶能力的作用。脉冲电流轧制后的镁合金板材组织由细小的等轴再结晶粒与析出相构成,没有发现孪晶组织,并且完全再结晶,原始晶粒均被细小的再结晶晶粒取代,再结晶晶粒内的位错密度低。而温轧镁合金组织则由稍拉长变形孪晶、粗大的再结晶晶粒和析出相构成,再结晶的晶粒内位错密度高。两种轧制方式下的镁合金析出相均为Mg17Al12。脉冲电流轧制后镁合金的织构具有典型基面织构的特征,而脉冲电流轧制镁合金的织构则出现横向偏转;脉冲电流轧制后镁合金的屈服强度与伸长率均比温轧镁合金的大,但抗拉强度正好相反。 相似文献
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在150-350℃温区内不同温度下轧制AZ31镁合金板,观察了不同温度下轧制变形量为9%的AZ31镁合金板材的显微组织,研究分析了轧制温度对轧制板材中{1011}-{1012}双孪晶的含量、类型以及高温轧制过程中双孪晶中的动态再结晶行为的影响,讨论了板材中的孪晶对其力学性能的影响.研究结果表明:在150-300℃温区内轧制时,板材组织中均有含量不等的{1011}-{1012}双孪晶,随着轧制温度的升高,孪晶含量下降.250℃以上轧制的板材中单片一次孪晶中出现的双孪晶类型较为单一,仅出现共面型双孪晶.在250℃以上轧制板材中的双孪晶晶界处中可以观察到明显的动态再结晶现象,这些动态再结晶晶粒对孪晶界和孪晶起到消除和吞噬的作用.350℃下轧制的AZ31镁合金板材中未观察到{1011}-{1012}双孪晶.随着轧制温度的升高,镁合金轧制板材的强度减弱而塑性增强. 相似文献
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Substructure development in an austenitic Ni–30%Fe model alloy was investigated within a dynamic recrystallization (DRX) regime. The substructure characteristics of the deformed matrix and DRX grains were markedly different regardless of the grain size and orientation. The former largely displayed ‘organized’, banded subgrain arrangements with alternating misorientations, resulting from a limited number of active slip systems. In contrast, the substructure of DRX grains was generally more ‘random’ and exhibited complex subgrain/cell arrangements characterized by local accumulation of misorientations, suggesting multiple slip. The proposed mechanism of the unique substructure development within DRX grains suggests that the DRX nuclei, forming along pre-existing grain boundaries and triple points, essentially represent grain boundary regions, which experience multiple slip to preserve the compatibility with neighbouring deformed grains. This results in the formation of a complex cell/subgrain structure, which progressively extends as the grain boundary regions expand outwards during DRX growth. 相似文献
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AZ31镁合金铸轧和常规轧制板的变形组织及形变特征 总被引:1,自引:1,他引:0
在变形温度为150~400 ℃、应变速率为0.3~0.000 3 s~(-1)条件下,在Gleeble1500热模拟机上采用等温拉伸试验对AZ31镁合金铸轧和常规轧制板的高温塑性及组织演变进行研究.结果表明:两种AZ31镁合金板的峰值应力和峰值应变均随着变形温度的降低和应变速率的增加而逐渐增大.铸轧板的应变硬化指数和应变速率敏感系数均大于常规轧制板的.在高温低应变速率变形条件下,铸轧板的晶界滑移引起的空洞尺寸、体积分数和密度均大于常规轧制板的.低应变速率下拉伸变形后的动态再结晶晶粒尺寸随温度的升高逐渐增加;不同变形条件下铸轧板的晶粒尺寸均小于常规轧制板的;再结晶晶粒尺寸和Z参数呈幂律关系. 相似文献
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对Fe-30%Ni合金和超低碳贝氏体钢在高温进行不同方式变形和保温,通过变形、回复、与再结晶,获得秒同的晶体缺陷数量与构型(主要是位错分布形态)。用硼径迹显微照相技术研究了 空冷过程中硼向晶界的非平衡偏聚及与不同形态晶体缺陷的关系。结果表明,在再结晶新晶粒冷却时晶界偏聚明显。晶界附近会出现较显著的贫硼现象,而变形并回复后的原始晶粒中此现象不明显,高温回复阶段形成的多边形化亚晶界(位错墙)对冷却时硼 相似文献
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