挤压态GH3625合金冷变形过程中的组织和织构演变

采用EBSD技术研究了挤压态GH3625合金冷变形过程中的组织演变、晶界特征分布、位错密度、应力分布及织构演变规律。结果表明,随着冷变形量的增加,晶粒变形程度加大,晶粒形貌由扁平状转变为细条状,晶体转动使得晶界与加载压力轴垂直分布;随着冷变形量的增加,大角度晶界逐渐向小角度晶界转变,孪晶界的比例逐渐增加。随着冷变形量的增加,局部取向差的平均值(■)升高,位错密度增加;同时,晶粒变形均匀性逐渐变好,应力集中分布逐渐向应力均匀分布转变。随着冷变形量的增加,其形变织构的类型基本保持不变,而具有稳定取向的Copper织构{112}111的强度略有降低;同时,由不均匀变形产生的Rotated-cube织构{001}110的强度降低;此外,形变孪晶的形成导致Goss织构{110}001和Brass-R织构{111}112的强度降低。     

Ti-IF钢罩式退火过程中再结晶织构演变规律研究

采用X射线衍射技术(XRD)和电子背散射衍射技术(EBSD),并结合微观组织观察分析了Ti-IF钢罩式退火过程中织构演变规律和{111}再结晶织构形成机制.结果表明:随退火温度的升高,再结晶量逐渐增多,{111}再结晶织构强度亦逐渐增强,同时{100}织构强度逐渐减弱.{111}取向的品粒主要在再结晶过程中形成,依靠吞并其他取向[主要是{100}取向]的晶粒而长大;并且在{111}取向品粒长大过程中,γ纤维织构之间也发生相互转化,主要由{111}<112>织构转变为{111}<110>织构;冷轧IF钢再结晶退火后具有较强的γ纤维织构,主要是"取向形核"和"取向长大"共同作用的结果,其中Σ重位晶界在再结晶γ纤维织构形成过程中起着重要作用.     

Ti-Nb-Ta-Zr-O合金冷变形及再结晶组织

采用电子背散射衍射(EBSD)对Ti-23Nb-0.7Ta-2Zr-1.20(摩尔分数,%)合金的冷旋锻变形组织和退火组织进行了研究.结果表明:Ti-23Nb-0.7Ta-2Zr-1.2O合金的变形组织中包含高密度的小角晶界,合金具有与棒材轴向平行的强烈<110>丝织构;在退火过程中,合金中的小角晶界密度逐渐降低,大角晶界数量逐渐增多并最终成为主要晶界;在退火过程初期,合金中出现了大量细小晶粒,且随着退火时间的增加,这些晶粒逐渐通过消耗变形组织长大,晶粒取向逐渐分散,表明Ti-23Nb-0.7Ta-2Zr-1.2O合金的再结晶通过传统的形核长大机制进行.     

立方取向50％Ni-Fe合金的二次再结晶织构的测定

面心立方的Ni-Fe二元合金,经过大压下量冷轧以后,形成了集中的冷轧织构,主要为{110}<112>+{112}<111>,将它在1000℃以下退火,通过一次再结晶可以形成晶粒很小但很完善的立方织构。这一现象曾引起物理冶金学者们很大的兴趣,并且很早就在工业上取得应用。 Rathenau曾用48％Ni-Fe合金作为试样对Ni-Fe合金的二次再结晶进行了详细的研究,得到     

MGH754合金挤压棒材的二次再结晶与织构

研究了ＭＧＨ７５４合金在二次再结晶过程中的组织和结构变化。结果表明，合金大热挤压状态具有细小的等轴晶组织，织构微弱，有利于进行殂变加工；二次再结晶后，组织为粗大的柱状晶，且出现强烈的织构；随着退火时间延长，「１１０」〈００１》和「１００」〈００１〉织构含量明显增加，而「１１０」〈１１１〉，「１１０」〈１１３〉和「１１２」〈１１１〉等织构的含量减少，合金棒材的纵向主要为〈００１〉取向。     

轧制Al—Mn合金再结晶过程中立方织构的形成

用微观织构分析法天空了轧制Ａｌ－Ｍｎ合金变形组织中的立方带、辩证喧形核及立方晶粒的生长。观察到两种形貌特征的立方带。立方带与其周围基体的取向梯度变化不具有Ｄｉｌｌａｍｏｒｅ－Ｋａｔｏｈ模型关于立方过渡带的特征。立方带中的亚晶及立方带上形成的新晶粒的取向为取向并有绕ＲＤ或ＴＤ的转动;随形变量的加大,绕ＲＤ转动的立方晶粒增多,绕ＴＤ转动晶粒逐渐消失;低温退火时,立方带形核并没有明显的优势;但立方晶粒的     

IC-218合金的再结晶织构及其形成机制

研究了IC 2 1 8合金冷轧 60 %后在 1 0 0 0°C退火中形成的织构 ,发现再结晶后晶粒取向分布漫散 ,这种情况早在再结晶形核阶段就已出现 ,并在随后的长时间退火中保持。相继出现几个弱的再结晶织构 ,它们都与冷轧织构之间存在与低Σ重合点阵相近的位向关系。这些结果可与显微组织的观察很好地相互印证 ,表明导致再结晶织构这些特点的基本原因是一般大角晶界失去明显可动性而以位错运动为机制的界面迁移则相对活跃。将以上结果与单相Ni3Al的再结晶行为进行对比 ,发现两者极为相似。由此对 76Ni 2 4Al 0 2 4B合金的晶界结构是否存在无序区的问题提供了新的信息。     

变形参数对Mg-Zn-Ce合金显微组织和织构的影响（英文）

采用Gleeble-1500热模拟试验机在不同温度(250,300,350°C)和应变速率(0.001,0.01,0.1s-1)下对Mg-6Zn-0.5Ce (质量分数,%)合金进行热压缩试验,采用光学显微镜和电子背散射衍射技术研究热压缩变形过程中合金的显微组织和织构演变。结果表明,由变形工艺决定的Zener-Hollomon参数对Mg-6Zn-0.5Ce合金的动态再结晶和织构具有重要影响。随着Zener-Hollomon参数的增大,未再结晶区的体积分数增大且动态再结晶晶粒尺寸减小。再结晶区的织构强度弱于未再结晶区的织构强度,这使经较高Zener-Hollomon参数变形的试样呈较高的织构强度。再结晶织构强度的增加与晶粒择优生长有关。     

锆合金热变形过程中的织构演变研究

本文选取了一种热轧退火态的锆合金板材沿着其板材法向(0°样品)及横向(90°样品)在700 ℃温度下以1/s应变速率进行压缩试验。利用电子背散射衍射(EBSD)技术对变形后样品的微观组织及织构进行表征,并利用粘塑性自洽模型(VPSC)确定了在低应变条件下的各滑移系及孪晶的相对开启量。微观组织揭示了在两种样品中均有动态再结晶的发生。再结晶晶粒的织构变化与变形晶粒的织构变化相似,表明了再结晶过程中的优先形核及长大过程不会影响织构的形成及变化。在0°样品中,基面滑移、柱面滑移和锥面滑移在变形初期阶段同时开启,但是在90°样品中,只有少量的锥面滑移在变形初期阶段开启。在90°样品中存在的高强度的<10-10>//RD 织构组分是由大量开启的柱面滑移造成的。此外,700 ℃温度下大量基面滑移的开启对织构形成起重要作用。     

镍基高温合金在变形热处理过程中的组织和织构演变

采用电子背向散射衍射技术研究了镍基高温合金冷变形和再结晶退火过程中的组织演变、晶界特征分布、应变分布及织构演变规律。结果表明,当冷变形量较小（ε≤45%）时,晶粒沿着轧制方向被拉长,呈扁平状于基体中均匀分布,应力主要集中在晶界和孪晶界（TB）附近,大角度晶界（HAGBs）和TBs逐渐向亚晶界（Sub-GBs）和小角度晶界（LAGBs）转变。同时,出现Goss织构 {110}<001>、Brass-R织构{111}<112>、Twinned-Copper织构{552}<115>和Copper织构{112}<111>。当轧制压下量超过70%时,晶粒形状逐渐从扁平变为纤维状,晶粒的变形均匀性逐渐变好,应变分布变得均匀,LAGBs开始占主导地位。同时,织构类型保持不变,但织构强度增加。在1120 ℃退火15 min后,孪晶的长度分数随着轧制压下量的增加而增加。同时,变形织构转变为再结晶织构,织构类型增加,但织构强度减弱。此外,当退火孪晶的比例增加时,Copper织构{112}<111>不断向Twinned-Copper织构{552}<115>转变,并且经过30%~80%轧制变形的试样产生织构{124}<211>。     

Microstructure evolution and recrystallization behavior of cold-rolled Zr-1Sn-0.3Nb-0.3Fe-0.1Cr alloy during annealing

The effects of cold-rolling reduction, annealing temperature, and time on recrystallization behavior and kinetics of cold-rolled Zr-1Sn-0.3Nb-0.3Fe-0.1Cr alloy were investigated using the Vickers hardness test, scanning electronic microscopy (SEM), transmission electron microscopy (TEM) and electron backscatter diffractometry (EBSD). The results show that the rate of the recrystallization increased with increasing annealing temperature and rolling reduction. Recrystallized grains nucleated preferentially at sites with high density dislocation and deformation stored energy and then grew into integral grains. Recrystallization texture changed from $〈10\overline{1}0〉$//RD to $〈11\overline{2}0〉$//RD. The grain orientation changed from random orientation to the orientation with the maximum misorientation around 30°. Recrystallization kinetics and maps were constructed based on the Johnson–Mehl– Avrami–Kolmogorov (JMAK) equation to derive parameters sensitive to the microstructure. The activation energies for recrystallization of 30%, 50% and 70% cold-rolling reductions were determined to be 240, 249 and 180 kJ/mol, respectively.     

Effects of electric field on recrystallization texture evolution in cold-rolled high-purity aluminum sheet during annealing

The effects of an external DC(direct current)electric field on recrystallization texture evolution in the cold-rolled aluminum sheets with 99.99%purity were investigated by means of X-ray diffraction techniques.The cold-rolled high-purity aluminum sheets were annealed for 60 min at 200,300 and 400℃,respectively with and without an external DC electric field of 800 V/mm.The results show that with DC electric field,the recrystallization cube texture is strengthened at the stage of grain growth. Possible reason for the strengthening of the recrystallization cube texture with the applied electric field may be attributed to both selected nucleation and selected growth of cube oriented crystal nuclei.     

AZ91镁合金热轧退火过程中的织构演变

将具有随机初始织构的工业 AZ91镁合金在450°C 进行均匀化热处理。经热处理后,合金中出现弱的{0001}-{1010}-{1120}三重纤维织构。经400°C热轧后,合金的变形织构是典型的(0001)基面,其基极沿轧制方向分裂。在450°C 退火36 h后,其残余变形织构中的基极沿基面分布更均匀,没有出现晶粒的异常长大。     

冷轧不同微量化学状态Al-Mn-Fe-Si铝合金的等温退火

通过3种不同热处理工艺使一种Al-Mn-Fe-Si合金获得了不同固溶液和不同尺寸及数量的弥散析出相,包括铸造态,一种富含高密度、细小、弥散相的状态,另外一种状态则仅有少量、相对粗大的弥散相。采用EBSD技术系统研究冷轧后退火过程中微观组织的演变以及初始组织状态对再结晶动力学、再结晶晶粒形貌和织构的影响。结果表明,再结晶动力学、最终微观组织和织构由加工条件和合金的初始组织和固溶度决定。高密度弥散析出相阻止形核,显著阻碍软化过程,最终得到粗大的狭长晶粒以及P和ND-rotated cube织构。在没有预先存在的细小、稠密的弥散相并且在退火过程中弥散相析出数量很少的时候则能更快完成再结晶并得到均匀、细小的等轴晶以及显著的立方织构。     

AZ31镁合金再结晶退火的准原位EBSD研究

对AZ31镁合金热挤压板进行室温轧制(形变量为8%)后,利用背散射衍射技术原位(in-situ EBSD)观测了轧制试样中不同类型的孪晶组织在再结晶退火过程中的取向演变。结果表明:退火过程中拉伸孪晶区域形成尺寸相对粗大的再结晶新晶粒,再结晶晶粒取向与拉伸孪晶的取向较为接近;压缩孪晶/双孪晶区域形成了细小的再结晶晶粒,再结晶晶粒偏离基面取向。孪晶再结晶显著影响镁合金在退火过程中的织构演变,轧制样品中,拉伸孪晶再结晶使得基面织构强度增强,压缩孪晶再结晶则可以在一定程度上弱化镁合金的基面织构。     

Dynamic recrystallization and texture development during hot deformation of magnesium alloy AZ31

The dynamic recrystallization(DRX) and texture development, taking place during hot deformation of magnesium alloy AZ31 with a strong wire texture, were studied in compression at 673 K (0.73 Tm). Two kinds of samples were machined parallelly to the extruded and transverse directions of Mg alloy rods. New fine grains are evolved at original grain boundaries corrugated at low strains and develop rapidly in the medium range of strain, finally leading to a roughly full evolution of equiaxial fine grains. Kink bands are evolved at grain boundaries corrugated and also frequently in grain interiors at low strains. The boundary misorientations of kink band increase rapidly with increasing strain and approach a saturation value in high strain. The average size of the regions fragmented by kink band is almost the same as that of new grains evolved in high strain. These characteristics of new grain evolution process are not changed by the orientation of the samples, while the flow behaviors clearly depend on it. It is concluded that new grain evolution can be controlled by a deformation-induced continuous reaction, i.e. continuous dynamic recrystallization(DRX). The latter is discussed by comparing with conventional, i.e. discontinuous DRX.     

The effect of precipitation on the evolution of recrystallization textures in an AA 8011 aluminum alloy sheet

The texture of an AA 8011 aluminum alloy sheet cold rolled by 95% showed a typical β-fiber, which runs from the copper orientation [C={112}〈111〉] over S [{123}〈634〉] to brass [B={011}〈112〉]. The development of annealing textures depended on annealing temperatures due to the interaction between precipitation and recrystallization. Upon annealing at a low temperature of 275°C, precipitation took place before recrystallization. This led to a weak recrystallization texture consisting of {011}〈122〉, {001∼〈100〉, and {hk0}〈001〉, among which the {011}〈122〉 orientation developed near large FeAl₃ particles as the main orientation and the cube [{001}〈100〉] orientation originating from the matrix was relatively weak. After annealing at 350 and 500°C, a strong cube texture developed along with a weak {011}〈122〉 orientation. When the cube orientation developed, the copper orientation disappeared most rapidly. These results were discussed based on the interaction between precipitation and recrystallization.     

Pb-Ca-Sn合金的变形与再结晶组织、微观结构和动力学

在室温下将Pb-0.08Ca-2Sn合金轧制到不同厚度。电阻率和显微硬度的测试结果表明,样品在80~120°C的温度区间退火时发生再结晶。XRD检测确定变形组织为Brass型,所测得的Lankford各向异性参数R及其变化与用自洽方法所推导的结果接近。R值随轧制方向角度的改变表明该合金具有平面各项异性和较差的延展性。合金在80~120°C的温度范围内退火时,在3×104s内完成再结晶,显示出保留变形组织并有新Cube组元出现。     

Static recrystallization behavior of hot-deformed magnesium alloy AZ31 during isothermal annealing

The static recrystallization of hot-deformed magnesium alloy AZ31 during isothermal annealing was studied at temperature of 503 K by optical and SEM/EBSD metallographic observation. The grain size change during isothermal annealing is categorized into three regions, i.e. an incubation period for grain growth, rapid grain coarsening, and normal grain growth. The number of fine grains per unit area, however, decreases remarkably even in incubation period. This leads to grain coarsening taking place continuously in the whole period of annealing. In contrast, the deformation texture scarcely changes even after full annealing at high temperatures. It is concluded that the annealing processes operating in hot-deformed magnesium alloy with continuous dynamic recrystallized grain structures can be mainly controlled by grain coarsening without texture change, that is, continuous static recrystallization.     

湿H2气氛下CGO硅钢初次再结晶织构演变行为

通过对湿H2气氛下,相同退火温度、不同退火时间的CGO硅钢初次再结晶样品进行金相组织观察,并进行了EBSD微观织构分析,研究了CGO硅钢初次再结晶过程中的组织及再结晶织构演变行为。结果表明,在湿H2气氛下,820℃保温,CGO硅钢初次再结晶过程约在120 s时完成。随着退火时间的延长,γ面上{111}<112>织构含量逐渐减少,{111}<110>织构先减少后增多,随着再结晶的完成,部分{111}<112>取向晶粒向高斯{110}<001>取向转化的同时,也向{111}<110>取向转化,高斯{110}<001>织构含量逐渐增多。高斯取向晶粒较多是由{111}<112>取向晶粒转化而来,同时也证明了CGO硅钢高斯取向晶粒的二次再结晶异常长大生长机制为择优形核。