电磁搅拌制备的Al-5Ti-1B对6061铝合金显微组织和力学性能的影响

采用电磁搅拌连续铸挤工艺制备Al-5Ti-1B晶粒细化剂,研究了Al-5Ti-1B添加量对6061铝合金显微组织与力学性能的影响。结果表明:添加质量分数为0.1%的Al-5Ti-1B,6061铝合金的显微组织从171μm的粗大枝晶细化成平均直径为70μm的等轴晶,合金的抗拉强度提高了26.47%,伸长率提高了50.91%。随着Al-5Ti-1B的质量分数从0.1%逐渐增加到0.5%,6061铝合金的晶粒进一步细化,抗拉强度和伸长率进一步提高,但晶粒细化效应逐渐减弱。当Al-5Ti-1B添加量为0.5%时,6061铝合金被细化为平均直径为37μm的等轴晶,合金的抗拉强度和伸长率分别为243 N/mm2和10.5%。与未添加Al-5Ti-1B的6061铝合金相比,抗拉强度和伸长率分别提高了42.95%和90.91%。     

粉末压制Al-5Ti-1B合金的显微组织与晶粒细化性能

采用气雾化工艺制备Al-5Ti-1B合金粉,然后压制成Al-5Ti-1B合金,研究了粉末压制Al-5Ti-1B合金的显微组织与晶粒细化性能,并与铸造Al-5Ti-1B合金进行了比较。结果表明:气雾化快速凝固可以抑制TiB_2粒子的团聚和细化TiAl_3相,使TiB_2粒子和TiAl_3相均匀分布在粉末压制Al-5Ti-1B合金的α(Al)基体上。在纯铝熔体中添加0.2%(质量分数)的粉末压制Al-5Ti-1B合金并保温2 min,可使纯铝的晶粒组织从粗大的柱状晶细化为平均直径为183μm的等轴晶。保温时间延长至180 min,纯铝的晶粒平均直径仍保持在229μm。与铸造Al-5Ti-1B合金相比,粉末压制Al-5Ti-1B合金具有更强的晶粒细化能力和抗细化衰退能力。     

超声制备Al-5Ti-1B晶粒细化剂的组织和细化效果

利用X射线衍射分析仪(XRD)、光学显微镜(OM)和扫描电镜(SEM)对施加不同超声振动处理制备的Al-5Ti-1B晶粒细化剂的微观组织进行观察和分析,并使用工业纯铝作为研究对象进行细化试验。结果表明,在Al-5Ti-1B晶粒细化剂制备过程中,施加超声振动处理能显著改善其组织和细化效果。连续超声处理10 min制备的Al-5Ti-1B晶粒细化剂中TiAl3相均为细小的块状,平均尺寸为12.4μm,TiB2颗粒弥散分布在铝基体中,对工业纯铝的细化效果最好,可将纯铝晶粒细化至307μm。     

比压和双细化剂对挤压铸造Al-Zn-Mg-Cu合金组织的影响

采用挤压铸造工艺制备了高速机车用Al-Zn-Mg-Cu合金传动空心轴,研究了比压和Al-5Ti-1B+Al-10RE双细化剂对挤压铸造Al-Zn-Mg-Cu合金传动空心轴微观组织的影响。结果表明,随着比压的不断增大,挤压铸造Al-Zn-Mg-Cu合金空心轴试样中初生α-Al晶粒的形状不断变得圆整,晶粒尺寸不断变小;当比压达到160MPa时,初生α-Al晶粒中粗大的树枝晶基本消失,试样组织为非枝晶组织,试样的平均晶粒直径为25μm,平均等效圆度为0.73;随着双细化剂中Al-5Ti-1B加入量的减少、Al-10RE加入量的增加,试样的平均晶粒直径显著减小,而试样的平均等效圆度变化不大,基本上在0.65～0.75之间;当添加1%的Al-5Ti-1B+3%的Al-10RE时,试样的平均晶粒直径为21μm,平均等效圆度为0.70。     

TiB2粒子尺寸分布对Al-5Ti-1B晶粒细化效果的影响

作为Al-5Ti-1B中起细化作用的主要物相,TiB₂的尺寸分布对晶粒细化效果有重要影响。采用外加TiB₂的方式来解决传统氟盐法原位生成TiB₂时,TiB₂相尺寸分布区间宽且难以准确控制和调整的问题,实现了TiB₂尺寸可控的Al-5Ti-1B制备,并通过细化试验和模型计算相结合的方式研究了TiB₂尺寸分布对Al-5Ti-1B在纯铝上细化效果的影响。结果表明,在0.2%的TiB₂添加量和1.5℃/s的冷却速率下,采用中值粒径分别为2.5μm和1.4μm的TiB₂制备的Al-5Ti-1B在纯铝上的细化效果相应为149.2μm和137.0μm,相比于采用氟盐法制备的Al-5Ti-1B进行细化处理时的275.6μm分别下降了46%和50%。将TiB₂尺寸分布向更为细小集中的方向调整将有利于Al-5Ti-1B细化效果的进一步提升。     

高品质Al-5Ti-1B合金线的组织与晶粒细化性能

采用等离子体发射光谱仪、光学显微镜、X射线衍射仪和扫描电镜,研究了高品质Al-5Ti-1B合金线的化学成分、显微组织和晶粒细化性能。结果表明,高品质Al-5Ti-1B合金线的Ti、B合金元素含量稳定,Fe、Si、V、K杂质元素含量低。合金线的组织均匀细小,无氧化夹杂物,TiAl3相平均尺寸为16.7μm,TiB2粒子平均尺寸为0.73μm。添加质量分数为0.2%的高品质Al-5Ti-1B合金线可使纯铝铸态晶粒细化到75.7μm,晶粒细化响应时间块,抗衰退能力强,适应铝熔体温度范围宽。研究结果可为细化剂生产企业和铝加工企业在生产、选用高品质Al-5Ti-1B合金线时提供参考。     

精炼处理对Al-Si-Mg合金熔体中TiB2粒子的影响

加入Al-5Ti-1B中间合金的Al-Si-Mg合金熔体,经N2气精炼处理后试样的晶粒尺寸较精炼处理前明显粗化,即精炼处理显著削弱了Al-5Ti-1B中间合金对Al-Si-Mg合金的细化效果。分析认为,精炼过程中一部分TiB2粒子及其聚集团极易被N2气泡捕获并游离出熔体,使异质形核衬底数目大幅减少。针对精炼对细化效果的不利影响,提出了两种解决方案,即采用Al-5Ti-0.6B-0.2C中间合金或先精炼后添加细化剂的操作工艺。     

镁合金细化剂Al-5Zr-1B合金的组织与细化性能

采用K2ZrF4和KBF4混合粉末与铝熔体直接反应制备镁合金晶粒细化剂Al-5Zr-1B合金,利用光学显微镜、X射线衍射仪和扫描电镜,研究了Al-5Zr-1B合金的显微组织及其对纯Mg和AZ31镁合金的晶粒细化作用。结果表明:Al-5Zr-1B合金中含有大量细小的ZrB2粒子,平均尺寸为0.2μm,ZrB2粒子作为异质形核核心使纯Mg和AZ31镁合金晶粒得到细化。随着Al-5Zr-1B合金添加量的增加,纯Mg和AZ31镁合金的晶粒尺寸逐渐减小。添加0.3%(质量分数)的Al-5Zr-1B合金,可使纯Mg晶粒从1400μm细化到120μm。添加0.6%的Al-5Zr-1B合金,可使AZ31镁合金晶粒从170μm细化到45μm。     

动态合成对制备新型Al-Ti-B-RE细化剂第二相粒子的影响北大核心CSCD

为进一步优化铝中间合金细化剂的组织,提升细化性能,采用动态合成工艺制备新型Al-5Ti-1B-1RE中间合金晶粒细化剂,并与常规制备工艺进行对比,对所合成的中间合金的微观组织、细化工业纯铝的效果及力学性能进行了分析。试验结果表明:动态合成工艺制备的新型Al-5Ti-1B-1RE中间合金细化剂中的第二相粒子在Al基体中分布更具有细小均匀性;细化工业纯铝时,细化效果更好,细化后工业纯铝的极限拉伸强度和伸长率得以提高。     

Al-5Ti-1B合金等通道转角挤压的组织和性能研究

研究了等通道转角挤压技术对Al-5Ti-1B合金的组织和性能的影响。采用等通道转角挤压技术，在室温下，对Al-5Ti-1B合金进行了4道次挤压试验，并运用x射线衍射仪、金相显微镜和扫描电镜等研究形变前后Al-5Ti-1B合金微观结构的变化。结果表明，等通道转角挤压技术可以细化晶粒，改善了第二相颗粒分布的均匀性，提高了Al-5Ti-1B合金的力学性能。随挤压次数的增加，大块状TiAl3相由20～80μm粗晶粒细化到10μm左右；呈团块状且分布不均的TiB2经挤压后，分布均匀。采用Bc路径，进行4道次等通道转角挤压后，Al-5Ti-1B合金的屈服强度由142．0MPa增加到221．4MPa，提高了56．1％，其维氏硬度由45．2增大到64．9，提高了43．6％。     

Grain Refining Efficiency of SHS Al-Ti-B-C Master Alloy for Pure Aluminum and Its Effect on Mechanical Properties

A new Al-5Ti-0.75B-0.2C master alloy was successfully prepared by self-propagating high-temperature(SHS)reaction from an Al-Ti-B_4C system with molten Al.Microstructure and phase characterization of the prepared Al-5Ti-0.75B-0.2C master alloy show that the nearly spherical TiC particles,hexagonal or rectangular TiB_2 particles,and blocklike TiAl_3 particles distribute uniformly in the aluminum matrix.Grain refining test on commercial pure aluminum indicates that Al-5Ti-0.75B-0.2C master alloy exhibits a better grain refining performance than Al-5Ti-lB master alloy.By addition of 0.2 wt%Al-5Ti-0.75B-0.2C master alloy,the average grain size of a-Al can be effectively refined to160 ± 5 μm from about 3000 μm,and the tensile strength and elongation are increased by about 20%and 14.1%due to the grain refinement.     

中间合金对A356.2合金细化的效果

采用铝业协会制订的TP-1型标准测试法,对Al-10RE、Al-5Ti-1B、Al-5Ti-1B-10RE等中间合金对A356.2合金的细化效果进行评价,以优化铝合金轮毂制造过程中合金熔体细化处理工艺。结果表明, Al-5Ti-1B-10RE中间合金中的RE不仅可以有效抑制晶粒尺寸的衰退,而且在一定程度上改善Ti、B、Sr对A356.2合金显微组织的细化和变质效果;TP-1型晶粒度检测法是一种简单、直观、准确的中间合金细化效果在线评价方法。     

A novel fading-resistant Al-3Ti-3B grain refiner for Al-Si alloys

Al-Ti-B refiners with excess-Ti perform adequately for wrought aluminum alloys but inefficiently in the case of foundry alloys. The high content of silicon in the latter, which forms silicides with Ti and severely impairs the refining potency of the nuclei, is known to be responsible for the poor performance. Hence, new grain refiners, such as Al-3B and Al-3Ti-3B master alloys with excess-B have been developed with well documented advantages for Al-Si alloys. It is very desirable to involve TiAl₃ particles in the Al-3Ti-3B master alloy to maximize its grain refining efficiency. However, fading phenomenon is a key drawback for application of the TiAl₃-containing refiners in aluminum foundry. In the present work, new Al-3Ti-3B grain refiners, containing TiB₂, AlB₁₂ and TiAl₃ particles were developed with an aim to prolong the acting time after inoculation. The results showed that inoculation of Al-7Si alloy with thus meliorated Al-3Ti-3B grain refiner has produced a fine grain structure which was approximately maintained up to 30 min.     

Grain refining technique of AM60B alloy by Al-Ti-B master alloy

The effects of grain refining parameters on grain size of AM60B magnesium alloy have been investigated using an Al-5Ti-1B master alloy as refiner; and an appropriate refining technique has been developed. The results indicate that the Al-Ti-B master alloy is an effective grain refiner for AM60B alloy and the grain size can be decreased from 348 μm to 76 μm. Raising the addition temperature or the pouring temperature is beneficial for grain refinement; while for the addition amount and holding time, there is an optimal value. The appropriate grain refining technique is that 0.3% Al-Ti-B master alloy is added at 780oC and then the melt is held for 30 min before pouring. The above phenomena can be explained by the refining mechanisms that have been proposed from the related studies on Al and Mg alloys and theoretical analysis.     

Effect of Al-5Ti-1B-1Re on the Microstructure and Hot Crack of As-Cast Al-Zn-Mg-Cu Alloy

High crack tendency is easy to occur during preparation of the castings and ingots of Al-Zn-Mg-Cu alloy, and it is most difficult to be solved due to the characteristics for the series alloy. As-cast microstructures and hot cracking tendency of Al-Zn-Mg-Cu alloy with different addition levels of Al-5Ti-1B-1Re were investigated in the paper. Moreover, solidification characteristics of the experimental alloys with different mass fractions of Al-5Ti-1B-1Re were analyzed, and the addition content of Al-5Ti-1B-1Re was optimized. These results indicate that the microstructure of the experimental alloys with Al-5Ti-1B-1Re refiner is fine obviously, the dendrite shape refined by Al-5Ti-1B-1Re becomes more globular, the grain boundary is smoother, and the SDAS is smaller compared with the alloy without Al-5Ti-1B-1Re. When the addition level of the grain refiner is less than 0.2%, the hot cracking tendency for the experimental alloy is reduced. The addition of 0.2% Al-5Ti-1B-1Re is best effective to improve the as-cast microstructures and hot cracking of Al-Zn-Mg-Cu alloy, and the best addition level of Al-5Ti-1B-1Re refiner is 0.2%.     

Effect of a grain refiner cum modifier on mechanical properties of Al-7Si and Al-11Si alloys

This study evaluates the influence of grain refiners/modifiers on the mechanical properties of the Al-7Si and Al-11Si alloys with an experiment of quantitative and qualitative correlations with the microstructure. Modification of Al-Si alloys with strontium additions and grain refinement with Al-Ti, Al-B and Al-T-B master alloy additions are demonstrated to be efficient on Al-Si alloys. A single master alloy with combined additions of Sr and Ti and/or B was prepared and the microstructure and mechanical properties were studied. The results show that boron rich (Al-3B-Sr and Al-1Ti-3B-Sr) master alloys are more efficient than Ti rich (Al-3Ti-Sr and Al-5Ti-1B-Sr) master alloys considering their combined grain refinement and modification effect on Al-7Si and Al-11Si alloys. However, the presence of Sr does not influence the grain refinement. Similarly, presence of grain refiner does not influence the modification of eutectic Si.     

Al-Ti、Al-Ti-C中间合金对AZ91D镁合金组织和性能的影响

研究了Al-5Ti、Al-5Ti-0．25C和Al-8Ti-2C中间合金对AZ91D镁合金的组织、力学性能和耐腐蚀性能的影响。结果表明,添加Al-5Ti中间合金使晶粒粗化,而添加Al-5Ti-0．25C和Al-8Ti-2C中间合金使晶粒细化,Al-8Ti-2C中间舍金的细化效果明显且细化后组织细小均匀;添加Al-5Ti中间合金使合金的力学性能降低,而添加Al-5Ti-0．25C和Al-8Ti-2C中间合金均使合金的拉伸强度和伸长率得到了提高;添加Al-5Ti、Al-5Ti-0．25C和Al-8Ti-2C中间合金均使合金的耐腐蚀性能得到了改善。对于AZ91D合金而言,Al-8Ti-2C中间合金是一种良好的晶粒细化剂。     

The grain refinement of 6063 aluminum using Al-5Ti-1B and Al-3Ti-0.15C grain refiners

The Al-Ti-B grain refiners containing boride nucleant particles are used to promote a uniform microstructure throughout aluminum ingots and to suppress the growth of columnar grains. In addition, for the last eight years a new generation of Al-Ti-C grain refiners has been used commercially in a wide range of alloy systems. This paper will compare the potency of the commercially available Al-5Ti-1B grain refiner with that of the Al-3Ti-0.15C grain refiner for the 6063 cast alloy. For more information, contact Gabriela Popescu, University Politehnica of Bucharest, Material Science and Engineering Faculty, Splaiuil Independentei 313, Bucharest, 77206 Romania. gabriella81us@yahoo.com.     

Effect of the salt addition practice on the grain refining efficiency of Al–Ti–B master alloys

The impact of the salt addition practice on the microstructure and grain refining efficiency of Al–Ti–B alloys produced by the “halide salt” route was investigated. The grain refining performance of an experimental Al–5Ti–1B master alloy was optimized when the halide salts were pre-mixed before addition to aluminium melt at 800 °C during the production of the grain refiner. The stirring action provided during salt addition was found to degrade, while a high rate of addition was found to improve, the grain refining efficiency. In view of the above, an improved salt addition practice to ensure an exceptional grain refining performance is claimed to comprise the following steps: melting commercial purity aluminium ingot; addition of pre-mixed salts to molten aluminium at 800 °C, at once to facilitate a rapid salt reaction, gently mixing the salts with the aluminium melt without introducing any stirring. The grain refiner master alloy thus produced gives an average grain size of 102 μm 2 min after inoculation.