Ti系细化剂及T6热处理对Al-Si-Mg合金组织与力学性能的影响

文章研究了添加0.2%Ti含量的Al-Ti、Al-Ti-B和Al-Ti-C三种晶粒细化剂对Al-Si-Mg合金组织和力学性能的影响。结果表明,含Ti细化剂降低了晶粒尺寸和二次枝晶间距。Al-Ti和Al-Ti-C改善共晶硅的形貌,提高合金的力学性能。但Al-Ti-B与合金中Sr产生毒化作用,使得共晶Si呈粗大的板片状,合金的铸态性能显著下降。铸态及T6态下,添加Al-Ti-C细化剂的合金均具有最高的强度与伸长率,T6态下,其抗拉强度为285 MPa,屈服强度为251 MPa,延伸率为5.5%。     

重熔保温时间对Al-Ti-C中间合金微观组织及细化性能的影响

利用Al、Ti、C粉末原料,采用铝熔体热爆法合成了相同成分不同微观组织形貌的两种Al-Ti-C中间合金晶粒细化剂。借助X射线衍射(XRD)、大型光学显微镜(MEF3)等分析手段研究了重熔保温时间对Al-Ti-C中间合金微观组织及细化效果的影响。结果表明:合成的两种Al-Ti-C中间合金均由Al、TiAl3和TiC组成。重熔时,保温时间对Al-Ti-C中间合金微观组织产生重要影响。随着重熔保温时间的延长,TiAl3会发生聚集、长大,而TiC颗粒有聚集倾向,但保温过程中,TiAl3和TiC相表现出较强的稳定性,并没有生成其他杂相如Al4C3等。重熔后的Al-Ti-C中间合金仍具有一定的晶粒细化能力。     

浅谈Al-Ti-C与Al-Ti-B细化剂对7050合金铸锭的影响

7050铝合金大量应用于航空航天结构件,在生产过程中熔铸工序的铸锭组织对最终产品质量有决定性影响。为了解不同晶粒细化剂对7050合金铸锭组织的影响规律,采用金相显微镜、扫描电镜等检测手段,分析了Al-Ti-C与Al-Ti-B两种细化剂对7050合金铸锭低倍晶粒度、显微疏松以及显微组织的影响。结果表明：Al-Ti-B在线细化能力优于Al-Ti-C;Al-Ti-C在线细化铸锭的显微疏松尺寸稍低于Al-Ti-B在线细化的铸锭;Al-Ti-B在线细化铸锭的富铁相呈针状形貌,而Al-Ti-C在线细化铸锭的富铁相形貌主要呈块状形貌。     

微量Si、Mg元素对细化剂作用效果的影响

研究了6063合金中的微量Si、Mg元素对Al-Ti-C中间合金细化效果的影响，并探讨了其影响机理。试验结果表明，当6063铝合金中同时存在微量的Si、Mg元素时，Al-Ti-C的细化效果会更加显著。     

Al-Ti-C细化剂制备过程中润湿及界面反应的研究

在材料的制备、加工过程中,液—固相间润湿行为和界面间相互作用这一物理化学现象是常被提及的,因为对其研究不但在理论上有重要意义,在实际工程中也是必须考虑的关键因素,它对于材料制备的可能和材料形成的性能起到了较大程度的决定作用[1]。本实验研究以Al-Ti-C晶粒细化剂合成中的润湿反应行为及反应过程当中的合金组织形成机制为重点,通过润湿与反应条件的优化,选用液-固反应法成功制备Al-5Ti-0.25C中间合金基础上,通过OM和SEM等技术方法,系统分析了合成参数对其合金组织演化的影响规律,分析探讨了润湿与反应机制。     

钛氟酸钾-木屑法制备Al-Ti-C母合金机制与显微组织研究

采用X射线衍射(XRD)、扫描电子显微镜(SEM)、能谱仪(EDS)等研究了氟盐-木屑法制备的Al-Ti-C母合金的组织性能。结果表明:由氟盐-木屑与铝液反应制备的Al-Ti-C母合金的合成过程包含以下几个阶段。(1)铝与钛氟酸钾反应置换出的钛与铝反应生成钛铝化合物;(2)木屑在高温条件下发生脱水、碳化反应,裂解产物二氧化碳、碳与铝反应生成碳铝金属化合物,与钛反应生成钛碳化合物;(3)钛铝、碳铝、钛碳化合物组成具有细化作用的Al-Ti-C母合金。合金的物相为α(Al)、铝钛化合物与碳铝化合物组成的共晶组织,其中α(Al)相的平均晶粒尺寸为10～60μm。铝钛化合物为棒状、骨骼状共晶组织并沿晶界分布,晶内可见针片状Al_3Ti,颗粒状TiC相聚合成团块状分布。木屑裂解产物水、二氧化碳与铝反应生成氧化铝和氢以渣-气共生的形式聚集于晶界。     

Al—Ti—C中间合金细化铝及Al—Zn—Mg—Cu1.5合金晶粒研究

三元中间合金Al-Ti-C是新研制的一种铝晶粒细化剂。在对高纯铝(99.99％)、工业纯铝(99.7％)及Al Zn-Mg Cu_(1.5)合金细化晶粒的研究中,证明其细化晶粒性能优于通常使用的Al-Ti二元及Al Ti B三元中间合金。用扫描电镜和电子探针等方法研究证实,当钛的加入量少于0.15％时,高纯铝的晶粒细化不是由包晶反应而是由TiC粒子引起的,从而证明了TiC理论。此外,在工业纯铝中残存某些杂质元素,对铝的晶粒细化也起重要作用。本文论述了使用Al-Ti-C中间合金细化铝晶粒的过程及从几方面证实了TiC生核理论。     

GH150合金棒材的热处理制度

通过组织观察、室温和600℃拉伸试验以及600℃持久性能试验，研究了不同热处理制度对GH150合金棒材组织和性能的影响。研究结果表明，固溶温度对合金组织和性能的作用较为明显。当固溶处理温度较低时，合金的晶粒较小，拉伸性能好，而持久性能较差；而固溶处理温度较高时则与之相反。一次及二次时效处理温度的变化对合金的拉伸性能影响不大，但对持久性能有一些影响。时效处理温度较低时，合金中析出的γ’相、碳化物等较细小、弥散。     

稀土Y强化金基微合金研究

研究了Y对Au-Zr-Ge金基微合金的组织结构和力学性能的影响，结果表明：Y能改善第二相的形态和分布，显著地提高合金的力学性能。通过分析Y的强化作用，提出了组织特征参数——第二相尺寸因子，以表征合金的组织结构对性能的综合影响。     

Al-Ti-C对铝合金组织性能影响的分析

以较为常用的6063铝合金为研究对象，文章分析了Al—Ti—C中间合金对其组织及性能的影响，并从理论上分析了Al—Ti—C的作用机理。结果表明，Al—Ti—C对合金组织具有强烈的细化作用，同时对其性能也有一定影响。最后对实验结果进行了分析与总结。     

Evaluation of Al-Ti-C Master Alloys as Grain Refiner for Aluminum and Its Alloys

Al-Ti-C master alloys have a great potential as efficient grain refiners for aluminum and its alloys. In the present work, the Al-Ti-C master alloys are synthesized via a relatively novel technique through the reaction of a compacted mixture of K₂TiF₆ and graphite with molten aluminum. The obtained alloys are examined using scanning electron microscopy (SEM), energy-dispersive spectroscopy, and X-ray diffraction (XRD) methods. The results indicate that the produced Al-Ti-C master alloys contain TiC and TiAl₃ particles within the aluminum matrix. Also, these alloys were evaluated using the KBI test mold. The results indicate that the produced Al-Ti-C master alloy is an efficient grain refiner for pure aluminum and its alloys compared with the Al-Ti-B one. The factors affecting the grain refinement of aluminum and its alloys are studied. The proper conditions for evaluating the efficiency of the produced Al-Ti-C master alloy to obtain a minimum grain size are as follows: temperature, 993 K (720 °C); holding time, 2 minutes; and (Ti/Al) weight ratio, 0.01 pct.     

Effect of Y Addition on Microstructure and Constituent Phases of Al-Ti-C Master Alloy

Al-Ti-C master alloy was prepared by SHS (Self-propagating High temperature Synthesis)-melting technique. Effect of yttrium addition level on the microstructures of the master alloy was studied by XRD, SEM and EDS. The experimental results show that the addition of 1.0%Y is beneficial to the formation of TiC particles; Al-Ti-C-1.0Y consists of rod-like and blocky TiAl3, TiC, Al3Y and α-Al matrix. Y is found around TiC particles in Al-Ti-C-0.5Y master alloy while blocky (AlTiY) phase appears in Al-Ti-C-1.0Y master alloy. Al3Y with dendritic morphology and small blocky Al2Y except for TiC are found in Al-Ti-C-2-0Y master alloy.     

7050铝合金晶粒细化剂的选择和应用

Zr元素对Al-Ti-B中间合金有严重的"毒化"作用,因此,在生产7050等含Zr的Al-Zn-Mg-Cu系超高强度铝合金时不宜使用Al-Ti-B中间合金细化晶粒。Al-Ti-C有效地改善了Al-Ti-B的缺点,降低偏聚倾向,对"中毒"起抑制或免疫作用。生产7050铝合金铸锭时,控制Zr含量小于0.12%,将铝熔体温度控制在730℃以下,使用Al-3Ti-0.15C中间合金细化晶粒不会产生细化"中毒",有很好的细化效果。     

Effect of La on Microstructure and Grain-Refining Performance of Al-Ti- C Grain Refiner

Al-Ti-C grain refiner was prepared by SHS （self-propagating high-temperature synthesis ）-melting technique. The effect of La on the microstructures of grain refiner was studied by OM, TEM, SEM, XRD, and EDS. The experimental results indicate that La can improve the wettability between liquid aluminum and graphite ; the addition of La results in dispersive distribution of TiAl3 and TiC particles in the matrix. An excellent grain refining performance of Al-Ti-C grain refiner on commercially pure Al was obtained.     

A study on the kinetic process of reaction synthesis of TiC: Part I. Experimental research and theoretical model

The micromechanism and the macrokinetic process of synthesis TiC in preparing Al/TiC by direct reaction synthesis (DRS) have been investigated in detail by observing the microstructure of the water-quenched preform by scanning electron microscopy (SEM) and energy* dispersive X-ray (EDX) analysis. The results have shown that the micromechanism of reaction is a solution-precipitation mechanism, in which carbon powders in the preform were surrounded by a Ti-rich Al-Ti-C melt layer and reacted with titanium in the layer to synthesize TiC particles, and TiC precipitated from the layer and scattered over the alloy melt. The macrokinetic model of reaction synthesis of TiC can be divided into four stages: heating and melting stage, initial reaction stage, complete reaction stage, and cooling stage. In the end, a macrokinetic model has been set up based on the experimental results.     

Synthesis mechanism of an Al-Ti-C grain refiner master alloy prepared by a new method

The mechanisms of in-situ synthesis of an Al-Ti-C grain-refiner master alloy, prepared by adding a powder mixture of potassium titanium fluoride and carbon into an aluminum melt, have been systematically studied. It was found that vigorous reactions occurred at the initial stage of reaction and then slowed down. After about 20 minutes, the reactions, which led the formation of blocky titanium aluminides and submicron titanium carbides in the aluminum matrix, appeared to reach completion. Potassium titanium fluoride reacted with aluminum and carbon at 724 °C and 736 °C, respectively, resulting in the formation of titanium aluminides and titanium carbides in the aluminum matrix as well as in the formation of a low-melting-point slag of binary potassium aluminofluorides. The reaction between potassium titanium fluoride and carbon is believed to be the predominant mechanism in the synthesis of TiC by this method.     

A Developed Method for Fabricating <Emphasis Type="Italic">In-Situ</Emphasis> TiC<Subscript><Emphasis Type="Italic">p</Emphasis></Subscript>/Mg Composites by Using Quick Preheating Treatment and Ultrasonic Vibration

Quick preheating treatment of the Al-Ti-C pellets and high-intensity ultrasonic vibration are introduced in the fabrication of in-situ TiC _p /Mg composites. Al-Ti-C pellets are preheated for about 130 seconds in the furnace at 1023 K (750 °C), in which magnesium is melted as well. In this process, plenty of heat can be accumulated due to the reactive diffusion between liquid aluminum and solid titanium in Al-Ti-C, and a small amount of Al₃Ti phase is formed as well. After adding the preheated Al-Ti-C into the molten magnesium, thermal explosion takes place in a few seconds. In the meantime, high-intensity ultrasonic vibration is applied into the melt to disperse in-situ formed TiC particles into the matrix and degas the melt as well. Microstructural characterization indicates that in-situ formed TiC particles are spherical in morphology and smaller than 2 μm in size. Furthermore, a homogeneous microstructure with low porosity of the magnesium composite is obtained due to the effect of ultrasonic vibration. A novel approach using the quick preheating treatment technique and high-intensity ultrasonic vibration to synthesize in-situ TiC _p /Mg composites is proposed in our research.     

Reactions during infiltration of

The infiltration sequence of graphite fibers with liquid aluminum alloyed with titanium was studied. The titanium concentration was chosen such that a severe reaction occurred between the fibers and the melt. Aluminum carbide and titanium carbide, as well as an aluminide phase were formed. The phenomenon occurring during the infiltration sequence was explained with the aid of the ternary-phase diagram Al-Ti-C. The effect of the reaction on the infiltration height is discussed.