AlTiC中间合金细化剂研究的最新进展

通过合适的工艺、并选择合适的成分,AlTiC对99.7％Al的细化效果完全可以和目前国际上最好的AlTiB相媲美。当细化1070、1060、1235、3004、6063及8011等合金时,AlTiC和AlTiB细化效果均优异且相当。当用对99.7％Al具有同样细化效果的AlTiC和AlTiB细化含Zr、Cr、Mn的铝合金时,未发现细化“中毒”现象,Zr和Mn还不同程度地加强了AlTiC和AlTiB的细化效果。TiC单独成为结晶核心的观点成立与否与TiC的加入方式和保温时间同时相关;用不含Al3Ti的AlTiC细化剂细化工业纯铝时,在保温60min时间内,这样的AlTiC可产生一定的细化效果;用纯TiC粉直接加入铝液时,当TiC粉在铝液中分散均匀后,即可产生显著的晶粒细化效果。     

Performance comparison of AlTiC and AlTiB master alloys in grain refinement of commercial and high purity aluminum

1 Introduction Since AlTiC master alloys were improved greatly as a new type of master alloy used in grain refinement of aluminum and aluminum alloys in the middle of 1980s[1, 2], there were many important progresses in the preparation techniques and the …     

制备多物相AlTiC合金的Ti与C熔体反应法

将Ti与C同时加入Al熔体可制备出Ti与C摩尔比分别大于、等于、小于4的3种含不同物相的Al—TiC合金：Al—TiAl3-TiC、Al—TiC、Al-Al4C3-TiC。对纯铝的细化实验表明：不含过量Ti的后两种合金的细化效果相近，Al4C3在Al—TiC合金中的大量出现不会进一步降低合金的细化能力；含TiAl3的第一种合金的细化效率远高于后两者的；TiC物相在基体中以离散颗粒或聚集团形式在Al基体中分布；Al4C3相极脆，易与空气中的水蒸汽反应而分解。分析表明Ti与C在Al熔体中反应生成TiC是通过两条途径同时进行的：熔体中的固体C颗粒与溶解态的Ti直接反应；固体C颗粒和Al反应生成的A4C3与溶解态的Ti发生反应。     

A356合金α(Al)的晶粒细化

采用 ＡｌＴｉＣ 晶粒细化中间合金对 Ａ３５６ 进行了晶粒细化试验,证明Ａ３５６ 合金的 α（Ａｌ）晶粒尺寸和枝晶干同时获得了明显的细化。这表明ＡｌＴｉＣ 合金可能是细化ＡｌＳｉ合金 α（Ａｌ）晶体组织和克服Ｓｉ中毒作用的良好晶粒细化剂。     

Al—Ti—C中间合金的相组成及其细化特性

用专利方法制备出各种成分的Al-Ti-C中间合金作为铝及铝合金的晶粒细化剂。对该系列中间合金的组织和物相分析表明：在制备中间合金过程中,C与Ti反应充分,生成TiC和TiAl3两种管二相,且TiAl3析出量取决于中间合金的Ti含量和Ti/C含量比。用于纯铝的晶粒细化试验表明：与Al-Ti-C中间合金相比,Al-Ti-C中间合金的晶粒细化效率更高;Al-Ti-C中间合金只有在组织中TiC与TiAl3保持适当比例时,才能对纯铝产生良好的晶粒细化效果,不含TiAl3的Al-Ti-C中间合金的晶粒细化作用很微弱;用Al-Ti-C中间合金细化纯铝晶粒时,响应时间短,但衰退较快,且不能通过熔体搅拌法予以消除。分析和探讨了Al-Ti-C中间合金的晶粒细化机理,认为“碳化物理论” 不能充分解释Al-Ti-C的晶粒细化机理,提出“Ti在TiC或TiAl3颗粒表面富集引发包晶反应”的晶粒细化机制。     

动态凝固Al-Ti-C中间合金组织与细化活性

采用CASTEX连续铸挤技术，对液．固反应法获得的Al-Ti-C中间合金熔体直接进行动态凝固成形，制备细化剂合金线材，计算模拟了动态凝固成形区的温度场和应力场，试验研究了动态凝固组织的形成机制及中间合金细化铝晶粒的特性。结果表明：熔体连续铸挤成形经历动态凝固、半固态挤压和塑性成形3个阶段，为动态凝固与成形过程；该过程对熔体的强烈剪切与热扰动作用，可改善中间合金的组织形态，显著提高其细化活性。     

Al–Ti–C–Sr master alloy—A melt inoculant for simultaneous grain refinement and modification of hypoeutectic Al–Si alloys

Present article is focused on the microstructural features of Al–Ti–C–Sr master alloy, an inoculant for simultaneous grain refinement and modification of hypoeutectic Al–Si alloys. This master alloy is basically a metal matrix composite consisting of TiC and Al₄Sr phases formed in situ in the Al-matrix. TiC particles initiate the refinement of primary α-Al through heterogeneous nucleation in molten hypoeutectic Al–Si alloy, while Al₄Sr phase dissolves in molten Al–7Si alloy enriching the melt with Sr, which eventually leads to modification of eutectic silicon during solidification of the Al–7Si alloy casting. Thus present master alloy serves in both ways, as a grain refiner and a modifier for hypoeutectic Al–Si alloys.     

Grain refining action of Al–5Ti–C and Al–TiC master alloys with Al–5Ti master alloy addition for commercial purity aluminium

Al–Ti–C master alloys have a great potential as efficient grain refiners for aluminium and its alloys. In the present work, the Al–5Ti–C, Al–TiC and Al–5Ti master alloys have been successfully prepared by a method of liquid solidification reactions. While the Al–5Ti–C master alloy consists of some strip- or needle-like TiAl₃, and in addition to TiC particles in the Al matrix, the Al–TiC master alloy revealed the presence of only TiC particles, and the Al–5Ti master alloy consists of only some blocky TiAl₃ particles. A united refinement technology by Al–5Ti–C+Al–5Ti and Al–TiC+Al–5Ti master alloys was put forward in this paper. The blocky TiAl₃ particles in Al–5Ti master alloy can not only improve the grain refinement efficiency of Al–5Ti–C and Al–TiC master alloys but also reduce the consumption because the blocky TiAl₃ particles improve the grain refinement efficiency of TiC particles in Al–5Ti–C and Al–TiC master alloys.     

铝中间合金的组织遗传效应

概述了铸造过程中中间合金组织遗传性的概念及其研究的发展过程,分析了中间合金组织遗传性对变质效果和最终铸件性能的影响,总结了中间合金组织遗传效应所需的物理条件。指出通过优选原材料、优化熔体处理工艺、研究开发新工艺等可以控制和利用中间合金的组织遗传效应,从而提高铸造铝合金的性能。此外,还指出了该领域发展的新方向。     

Grain Refinement of Aluminium by Master Alloy AlTi6C1

For the grain refinement of super pure aluminium and commercial pure aluminium,Al-Ti-C master al-loy is better than Al-Ti alloy.It was shown by scanning electron microscope(SEM)and electron-probe mi-croanalyser(EPMA)that when the amount of titanium added is less than 0.15%,grain refinement of superpure aluminium is due to TiC particles rather than peritectic reaction.In addition,the presence of impurityelements in commercial pure aluminium plays an important role in grain refinement.The process of grain re-finement of aluminium by TiC is discussed in light of the TiC thesis.     

高能超声处理对Al-Ti-B中间合金组织和细化效果的影响

在Al-Ti-B中间合金晶粒细化剂的制备和重熔过程中施加高能超声处理,研究了超声处理对中间合金组织和细化效果的影响。结果发现:重熔Al-Ti-B中间合金过程中施加高能超声处理对其微观组织形态和细化效果没有太大影响;混合熔盐反应制备Al-Ti-B中间合金过程中施加超声处理,在超声波的声空化和声流效应协同作用下,可以加速反应的进行,使合金中TiB2粒子的分布更为分散,形成大量细小块状或杆状的TiAl3相,从而提高了细化效果。     

AlTiB中间合金细化效果的组织遗传效应

通过对比试验发现：不同组织的Ａｌ－５Ｔｉ－１Ｂ中间合金具有不同的细化效果。借助金相，ＳＥＭ和ＴＥＭ等手段对组织进行了分析对比，探讨组织遗传对细化效果的影响。实验结果表明：利用快速凝固法制备的该中间合金，其块状ＴｉＡｌ３化合物细小，ＴｉＢ２等微小粒子分布弥散，具有最佳的细化效果。     

Al-Ti-C晶粒细化剂的连续铸挤组织与细化性能

采用液固反应法制备了Al-Ti-C中间合金,由常规铸造及连续铸挤成形,获得了不同组织形态的晶粒细化剂,并通过细化纯铝试验,研究了晶粒细化剂的组织形态与其细化效果间的关系。结果表明:熔体连续铸挤成形过程,对熔体的强烈剪切与热扰动作用,可分散细化TiAl3,使TiC粒子呈弥散分布,显著提高AlTi5C 0.25合金的组织细化活性,经连续铸挤成形的Al-Ti-C晶粒细化剂,特别适于对铝箔制品的细化处理。     

Grain refinement of AZ31 magnesium alloy by new Al-Ti-C master alloys

New Al₄C₃-containing Al-Ti-C master alloys (Al-0.6Ti-1C and Al-1Ti-1C) were developed by introducing Ti element into Al-C melt using melt reaction method, in which most of the TiC particles distribute around Al₄C₃ particles. It is believed that most of the C firstly reacts with Al melt and form Al₄C₃ particles by the reaction Al(l)+C(s)→Al₄C₃(s), and after adding Ti into the Al-C melt, the size of Al₄C₃ particles is decreased and the distribution of Al₄C₃ is improved through the reaction Ti(solute)+Al₄C₃(s)→TiC(s)+Al(l). With the addition of 1% Al-1Ti-1C master alloy, the average grain size of AZ31 is reduced sharply from 850 μm to 200 μm, and the grain morphology of α-Mg transits from a fully-developed equiaxed dendritic structure to a petal-like shape. Al-C-O-Mn-Fe compounds are proposed to be potent nucleating substrates for primary Mg. Appropriate addition of Ti is believed to increase the grain refinement efficiency of Al₄C₃-containing Al-Ti-C master alloys in AZ31 alloy.     

Al-8Ti-2C对Al-P中间合金变质效果的促进作用

研究了自制Al-P中间合金对共晶及过共晶Al-Si的变质作用，发现该Al-P中间合金对共晶及过共晶Al-Si合金都具有优良的变质效果。同时还发现，当铝合金熔体中加入Al-8Ti-2C中间合金时，Al-P中间合金对两类Al-Si合金的变质效果会增强。当Al-24Si合金中TiC含量为0．03％(以Al-8Ti-2C中间合金方式)时，初晶Si的平均尺寸由原来的47μm细化为41μm，最大尺寸由原来的75μm降为55μm；加入Al-P中间合金和TiC颗粒50min后，就可以出现变质效果，时间再延长，变质效果也不会有更大的提高。当Al-12Si合金中TiC含量为0．03％时，初晶Si的平均尺寸由原来的50μm变为30μm。     

United modification of Al-24Si alloy by Al-P and Al-Ti-C master alloys

The modification effect of a new type of Al-P master alloy on Al-24Si alloys was investigated.It is found that excellent modification effect can be obtained by the addition of this new type of Al-P master alloy into Al-24Si melt and the average primary Si grain size is decreased below 47μm from original 225μm.It is also found that the TiC particles in the melt coming from A18Ti2C can improve the modification ffect of the Al-P master alloy.When the content of TiC particles in the Al-24Si melt is 0.03%.the improvement reaches the maximum and keeps steady with increasing content of TiC particles.Modification effect occurs at 50 min after addition of the Al-P master alloy and TiC particles,and keeps stable with prolonging holding time.     

Mg对Al-Ti-B、Al-Ti-C中间合金细化铝晶粒效果的影响

试验研究了Mg对Al-5Ti-1B和Al-5Ti-0.2C两种中间合金细化铝晶粒效果的影响,分析了Mg影响两种中间合金细化铝晶粒行为的机制。结果表明,在w(Mg)=1%～7%的范围内,镁含量的增加,对两种中间合金细化铝晶粒的促进作用不显著,但对晶粒形貌有显著的影响;晶粒形貌取决于所用中间合金的种类和Mg添加量大小,相同镁含量时,用Al-5Ti-1B细化比用Al-5Ti-0.2C细化后晶粒的树枝化程度小;细化所用的中间合金相同时,随着镁含量的增加,细化晶粒的树枝化程度增大。     

变形对中间合金细化剂组织及细化性能的影响

研究了挤压变形对铸态Ａｌ－Ｔｉ,Ａｌ－Ｔｉ－Ｂ和Ａｌ－Ｔｉ－Ｃ中间合金的微细胞及其细化性能的影响,变形引起铸态中间合金中的Ａｌ３Ｔｉ相断开,并使团簇状ＴｉＢ２和ＴｉＣ粒子趋于分散。变形使３种铸成中间合金的细化性有分别产生了不同的变化,初步探讨了原因。     

Processing Effects on Grain Refinement of AZ31 Magnesium Alloy Treated with a Commercial Al-10Sr Master Alloy

The effects of Sr amount and melt holding time on the grain refinement of AZ31 magnesium alloy treated with a commercial Al-10Sr master alloy are investigated. The effects of solutionizing, rolling, and remelting of commercial Al-10Sr master alloy on the grain refinement of AZ31 magnesium alloy are also investigated. An increase in Sr amount from 0.01 to 0.1 wt.% or melt holding time from 20 to 80 min causes the grain size of AZ31 alloy treated with the commercial Al-10Sr master alloy to gradually decrease. In addition, the solutionizing, rolling, or remelting of commercial Al-10Sr master alloy can improve the refinement efficiency of the master alloy to AZ31 alloy, and the improvement resulting from the remelting is best obvious, followed by rolling and solutionizing, respectively.     

Fabrication of cast carbon steel with ultrafine TiC particles

The carbon steels dispersed with ultrafine TiC particles were fabricated by conventional casting method. The casting process is more economical than other available routes for metal matrix composite production, and the large sized components to be fabricated in short processing time. However, it is extremely difficult to obtain uniform dispersion of ultrafine ceramic particles in liquid metals due to the poor wettability and the specific gravity difference between the ceramic particle and metal matrix. In order to solve these problems, the mechanical milling (MM) and surface-active processes were introduced. As a result, Cu coated ultrafine TiC powders made by MM process using high energy ball milling machine were mixed with Sn powders as a surfactant to get better wettability by lowering the surface tension of carbon steel melt. The microstructural investigations by OM show that ultrafine TiC particles are distributed uniformly in carbon steel matrix. The grain sizes of the cast matrix with ultrafine TiC particles are much smaller than those without ultrafine TiC particles. This is probably due to the fact that TiC particles act as nucleation sites during solidification. The wear resistance of cast carbon steel composites added with MMed TiC/Cu-Sn powders is improved due to grain size refinement.