共查询到18条相似文献,搜索用时 125 毫秒
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镁合金超塑性的变形机理﹑研究现状及发展趋势 总被引:3,自引:0,他引:3
综述不同成形条件下的镁合金激活能及本构方程,对粗晶和细晶镁合金的超塑性变形机理予以详细的介绍。并对常见的几种镁合金超塑性加工方式进行探讨,并概述超塑性镁合金的发展趋势,认为未来超塑性镁合金将取得快速发展。获得高应变速率与低温超塑性镁合金并实现镁合金低成本化、安全化、环保化是目前研究的热点。 相似文献
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MB26镁合金的超塑性与超塑挤压研究 总被引:6,自引:0,他引:6
研究了MB26镁合金的超塑性,找到了该合金的最佳超塑性条件,分析了变形速率、温度等因素对该合金超塑性的影响。另外还对该合金的超塑性挤压作了实验研究。 相似文献
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镁合金作为当前最轻的金属结构材料,由于其独特的优点被誉为"21世纪绿色工程材料"。介绍了超塑性特征;阐述了镁合金细晶超塑性的方法及机理;分析了不同晶粒细化工艺对镁合金微观组织和塑性变形性能的影响,最后展望了镁合金超塑性的发展方向。 相似文献
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《特种铸造及有色合金》2015,(7)
采用喷射沉积技术制备Mg-9Al-3Zn-1Mn-6Ca镁合金沉积坯,并对其进行挤压预变形和二次热压缩变形,研究热变形过程中再结晶、超塑性之间的微观组织演变。结果表明,二次热压缩变形后的镁合金在350℃、0.002s-1变形速率条件下,实现了镁合金超塑性压缩变形,外缘圆周伸长率达到103.96%;超塑性变形发生时伴随着动态再结晶发生,且当加工硬化速率与软化速率达到动态平衡时会出现压缩超塑性,350℃时变形速率是影响高Ca镁合金超塑性的主要因素。 相似文献
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AZ31镁合金超塑性及其变形机制图 总被引:1,自引:0,他引:1
在温度为400~440 ℃、应变速率为10-2~10-4 s-1范围内,研究挤压态AZ31镁合金的超塑性.结果表明,当应变速率较高时,颈缩是超塑性断裂的主要原因.温度越高,应变速率敏感指数m值越大, AZ31镁合金的超塑性伸长率越高.当应变速率较低时,空洞扩张是影响超塑性断裂的主要原因,温度越高,超塑性伸长率越低.研究了超塑性变形机理,建立了超塑性变形机制图,结果表明,温度为400 ℃或420 ℃、应变速率较低时,AZ31镁合金的超塑性变形属于溶质拖曳的位错蠕变机制;当应变速率较大时,属于攀移控制的位错蠕变机制.温度为440 ℃时,AZ31镁合金的变形机制符合晶格扩散控制的位错蠕变. 相似文献
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采用分步变形法对TA15合金在10 kN高温电子拉伸试验机上进行了超塑性拉伸试验,研究了变形温度和预变形量对该合金超塑性性能及微观组织演变。结果表明:变形温度为850~950℃和预变形量为100%~200%时,TA15合金呈现出良好的超塑性;变形温度为900℃和预变形量为150%时,该合金的超塑性能最好,最大延伸率为1456%;变形温度为950℃时,该合金的超塑性能降低,延伸率仅为188%。TA15合金的微观组织状态显示:该合金在拉伸变形过程中微观组织保持等轴状,但是随着变形温度的升高,晶粒开始长大,变形温度越高,晶粒长大越显著。 相似文献
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A. A. Kishchik A. V. Mikhaylovskaya V. S. Levchenko V. K. Portnoy 《The Physics of Metals and Metallography》2017,118(1):96-103
The influence of a 3–10% content of magnesium in Al–Mg–Mn(Cr) alloys on the characteristics of the microstructure of sheet blanks and their superplasticity has been examined. It has been shown that the minimum size of grains and the best superplasticity are characteristic of the alloy that contains about 7% magnesium and is additionally alloyed simultaneously with manganese and chromium. An increase in the content of magnesium leads to the formation of conglomerates of particles of a chromium–manganese phase and, as a result, to a coarsening of the grain structure and a deterioration of superplasticity. 相似文献
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Microstructure evolution and superplastic behaviors of ZK40 magnesium alloy were investigated in the temperature range of 473~623 K. Transmission electron microscopy (TEM) was used to study the microstructure changes, twinning occurred significantly after being processed by equal channel angular pressing (ECAP) for one pass through the die, the mean grain size was 5.6μm. Finer grains can be obtained after further processing through ECAP, the average grain size of the alloy processed by ECAP for three passes was as low as 0.8 μ_m; this alloy exhibited low temperature superplasticity at 473~523 K, elongations obtained at the same initial strain rate of 1×10~(-3) s~(-1) were 260% at 473 K and 612% at 523 K, respectively. Corresponding values for the ZK40 alloy processed by ECAP for only one pass were 124% at 473 K and 212% at 523 K, respectively; poor superplastic behavior of this material was related to the long-range stresses associated with the non-equilibrium grain boundaries within the coarse grains. The incompatibility between fine and coarse grains was thought to be unfavorable to the improvement of superplasticity. 相似文献
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It is well known that duplex stainless steels having refined grain, structure exhibit superplasticity. In this paper, the
diffusion of boron in the superplastic duplex stainless steels has been investigated. Boron diffuses through the interior
of the grains in superplastic duplex stainless steels. On the other hand, in case of normal duplex stainless steel having
the same chemical concentration, boron mainly diffuses along the grain boundaries and does not diffuse through the interior
of the grains. Investigations using Auger electron microscopy for super plastic duplex stainless steels revealed, the Cr concentration
is much higher than Fe concentration in boron diffused areas. These results indicate that superplasticity activates diffusion
into the interiors of grains. Further, it seems that boron preferentially reacts with Cr rather than Fe. Moreover the distribution
of Fe and Cr is changed by the diffusion of boron. 相似文献
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简述了块体非晶合金的研究现状及其超塑性成形技术,重点介绍了温度及应变速率对非晶合金超塑性的影响、块体非晶合金过冷液相区本构模型研究概况以及超塑性成形的应用,提出了块体非晶合金超塑性研究中仍需解决的问题。 相似文献