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摘要镁合金性能优良从而受到人们的的关注，但是由于镁合金在室温下的塑性较低而在生产过程中受到很大的限制。由于镁合金是密排优尔方结构，孪生在镁合金室温的塑性形变中起着重要的作用，对此研究孪晶种类，数量对镁合金材料性能的影响有着重要意义。37763
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本文以AZ61镁合金作为研究对象，通过对进行过异温，异变形量，同步，异步，差温等不同工艺轧制后的AZ61镁合金进行实验，并且对部分轧制后的镁合金进行热处理。借助力学性能分析，金相观测，断口形貌观察，EBSD检测等分析手段，研究了AZ61镁合金中孪晶的数量，种类对材料性能的影响。主要的研究内容和结果如下：
由于镁合金属于密排优尔方结构，在室温下独立滑移系较少，所以孪生就成了主要的塑性形变方式。在225℃同温轧制时，主要产生的孪晶种类为{l0 2}拉伸孪晶和{l0 1}压缩孪晶的双孪晶组织同时还伴有部分拉伸孪晶和压缩孪晶。其中拉伸孪晶需要较少的启动应力，所以主要产生在塑性形变中前期，主导形变产生，而压缩孪晶主要产生在塑性形变中后期，容易导致应力集中区，导致材料性能下降。当孪晶产生时，这些孪晶可以提供附加的独立滑移系，提高材料性能，增大动态再结晶的温度范围，细化晶粒，提高均匀塑性变形能力。随着轧制温度的上升，在265℃同温轧制时，产生的孪晶数目有所减少，但是材料的性能有所增强。与同温轧制相比，异温轧制的材料，在40℃差温轧制时，孪晶数目更少，但是轧制出来的材料性能却更好。总结原因是由于材料内部组织发生变化，发生再结晶，晶粒尺寸以及晶粒均匀度上都更加均匀细小，再加上部分剩余孪晶组织产生的作用，从而使得材料整体的性能提高。
毕业论文关键词： 镁合金；拉升孪晶；压缩孪晶；双孪晶
The influence of twin of AZ61 material mechanical properties
Abstract
Excellent performance of magnesium alloy so as to get the attention of people，but because of magnesium alloy at room temperature with low plasticity and a lot of restrictions in the process of production. Because of magnesium alloy is close the six-party structure， magnesium in the twin room temperature plays an important role in plastic deformation，this study twin types，number of effect on the properties of magnesium alloy material has important significance.
Based on AZ61 magnesium alloy as the research object， through the different temperature， different deformation，synchronous and asynchronous，rate-of-rise AZ61 magnesium alloy after different process，such as rolling experiment，and on parts of the rolling of the magnesium alloy after heat treatment.With the aid of mechanical performance analysis，metallographic observation， fracture morphology observation， EBSD analysis means such as detection， the number of twin AZ61 magnesium alloy was studied， type on the properties of materials.The main research contents and results are as follows:
With temperature in 225 ℃ when rolling，mainly produced by twin types are {l0 2} tensile twin and {l0 1} compression twin pairs of twin organization at the same time accompanied by twin and compression twin part drawing. Among them due to stretching twin requires less stress， so early in the plastic deformation are usually produced， the dominant deformation，and compression twin main produce in the middle and later periods of the plastic deformation，easy to cause stress，high，led to the decrease of the material performance. As the rolling temperature rising，the number of twin has decreased. But the performance of the material， Compared with rolling temperature，different temperature rolling material，less number of twin， but rolling out material performance is better. Summarize the reason is because when twin produce，these twin can provide additional independent slip system， improve the material performance，increases the size of dynamic recrystallization temperature range，refine the grain，improve uneven plastic deformation ability. Material internal organization change at the same time，the grain size and small grains evenness are more uniform，so as to make the material's overall performance improvement.
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