合工艺制备半固态A356铝合金浆料的研究

将晶粒细化处理引入低过热度浇注和弱电磁搅拌技术中,形成了制备半固态合金浆料的复合工艺.应用复合工艺制备了半固态A356铝合金浆料,研究了复合工艺对所制备的半固态初生0相形貌和尺寸的影响.研究结果表明,细化处理的液态A356铝合金经低过热度浇注和弱电磁搅拌可制备具有颗粒状和蔷薇状初生α相的半固态浆料,并且浇注温度可适当提高.与未经细化处理的A356铝合金试样相比,细化处理可显著改善A356铝合金中初生α相的晶粒尺寸和颗粒形貌及其沿铸锭径向上的分布.     

Y对A356铝合金半固态初生相形貌的影响

利用低过冷度浇注工艺制备了A356铝合金半固态浆料,研究了稀土Y对合金半固态初生相形貌的影响。采用正交设计方法,优化了A356铝合金半固态初生相形貌的影响因素,通过直观分析与方差分析表明,经稀土Y变质处理及低过冷度浇注获得A356半固态初生球晶的最佳工艺条件:浇注温度为595℃,保温时间为3min,Y的加入量为0.5%。此时其晶粒在铸态下的形状因子为0.7,等积圆直径为49.6μm,其中浇注温度是晶粒形貌和尺寸的最主要影响因素,可信度达到95%;其次是Y的加入量和保温时间。     

Al-5Ti-B和稀土Y复合添加对A356合金半固态凝固组织的影响

采用稀土Y及Al-5Ti-B中间合金对A356铝合金进行细化处理,并用低温浇注技术制备半固态坯料.研究了单独添加Al-5Ti-B和稀土Y以及两者复合添加时对A356铝合金半固态凝固组织的影响.研究结果表明,Al-5Ti-B和稀土Y对A356铝合金半固态初生相的形貌及尺寸均有不同程度的改善.将两者复合添加时,可显著提高合金中初生相的形貌及尺寸,得到细小、圆整且分布均匀的半固态组织,其添加量的最佳组合为0.02％的Ti与0.5％的Y.探讨了两者复合添加对合金凝固组织的细化机理.     

浇注温度和ECAP对铝合金坯料组织的影响

采用近液相线法结合新SIMA法复合工艺制备半固态A356铝合金坯料,研究了浇注温度、等径角挤压（ECAP）和半固态处理温度、时间对坯料组织的影响。结果表明,适当的工艺参数可以制备出球状初生α—Al相晶粒的半固态A356铝合金坯料,其中较合理的工艺参数为：近液相线浇注温度为610℃,半固态保温温度为580℃,半固态保温时间为20min。     

半固态铝合金钛、硼细化工艺研究

采用钛硼细化工艺,结合低温浇注方法,制备了ZL104铝合金半固态坯料,并将坯料重新加热至半固态温度进行等温处理.实验结果表明:钛硼有效地细化了合金的铸态组织,半固态重熔过程中可获得球形初生α-Al晶粒,浇注温度越低,铸态组织越细,球形初生α-Al晶粒组织越好.     

稀土La对半固态A356铝合金凝固组织的影响

利用Al-La中间合金对A356铝合金进行了细化处理,并用低过热度浇注技术制备了半固态A356铝合金浆料,研究了细化处理对半固态A356铝合金初生α相形貌和尺寸的影响.研究结果表明,细化处理的A356铝合金经低过热度浇注可制备具有颗粒状和蔷薇状初生α相的半固态浆料,稀土La可显著改善半固态A356铝合金中初生α相的晶粒尺寸和颗粒形貌.探讨了稀土La对半固态A356铝合金初生α相的细化机理.     

熔体浇注温度和板倾斜度对倾斜板制备A356铝合金的凝固和显微组织的影响(英文)

采用倾斜板制备A356铝合金半固态浆料。通过倾斜板底部的逆流水冷却使A356合金熔体在流下倾斜板时发生局部凝固,从而导致在板壁上形成连续柱状枝晶。由于强制对流作用,这些树枝晶被折断成等轴和破碎的晶粒,然后被连续冲洗而在斜板出口形成半固态浆料。熔体浇注温度是影响凝固组织的重要条件,而倾斜度为优质半固态浆料提供必要的剪切作用。将得到的浆料在金属模具中凝固以制备理想显微组织的半固态铸造坯料。然后,通过热处理以提高半固态铸造坯料的表面质量。对半固态铸造和热处理后坯料的显微组织进行分析。研究熔体浇注温度(620,625,630和635°C)和板倾斜度(30°,45°,60°和75°)对斜板制备A356铝合金的凝固和显微组织的影响。结果表明:在625°C的熔体浇注温度和60°斜板倾角时,A356铝合金具有细小和球状的晶粒,是最佳的显微组织。     

S-EMS复合作用对A356铝合金半固态组织形貌的影响

研究了蛇形通道制备A356铝合金半固态浆料时，浇注温度和通道数量对半固态坯料中心和边缘微观组织的影响。并结合蛇形通道与螺旋磁场电磁搅拌，开发了一种新型的半固态制浆方法——S-EMS，研究了高过热度浇注对A356铝合金半固态浆料初生形貌和尺寸的影响。结果表明：在不加任何处理时，显微组织具有明显的枝晶特征，部分枝晶臂长度甚至超过200μm。采用蛇形通道制备半固态浆料时，随着浇注温度的降低或通道数量的增加，试样中心与边缘的平均晶粒尺寸均不断减小并趋于平缓，形状因子不断增加并逐渐趋于平缓，但从3个通道增加至4个通道时，心部形状因子略微降低。S-EMS法在浇注温度680℃下制备出平均晶粒直径78.68μm，形状因子0.65的微观组织，即使在高过热度浇注条件下也能制备出良好的半固态组织。当浇注温度降至660℃，制备出平均晶粒尺寸和形状因子分别为70.25μm及0.71的具有理想微观组织的半固态坯料。     

Al-Sc共晶反应对半固态A356合金初生α相的影响

利用低过热度浇注和等温保温技术制备了半固态A356-Sc铝合金浆料,研究了Sc对所制备的半固态A356铝合金初生α相形貌和尺寸的影响。结果表明:细化处理的半固态A356-Sc铝合金经低过热度浇注和等温保温可制备具有球状和颗粒状初生α相的浆料,稀土Sc可显著改善A356铝合金中初生α相的尺寸和形貌。获得了制备半固态A356-Sc合金浆料合适的工艺条件:Sc加入量为0.6 mass%,保温温度为630℃,保温时间为200 s,此时,初生α相的等效圆直径达到36.48μm,平均形状因子为0.85。探讨了Al-Sc共晶反应对半固态A356铝合金初生α相细化机理。     

稀土元素和浇注温度对Al-4.5Cu合金初生相形貌的影响

研究了不同稀土(RE)加入量和浇注温度对Al-4.5Cu合金初生相形貌的影响.结果表明:添加微量的RE并降低合金的浇注温度,可获得非枝晶组织的半固态Al-4.5Cu合金坯料;添加了0.5%RE的合金,随浇注温度的降低,其初生相由树枝晶转变成细小的球状晶粒;当浇注温度为660℃,随RE加入量的增加,合金的初生相由等轴枝晶转变成细小的蔷薇状晶体,最后转化为球状晶粒;未添加RE的合金,随浇注温度的下降,其初生相由发达的树枝晶转变成等轴枝晶.     

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.     

Preparation of Ni-W-10Y_2O_3 refiner and refinement mechanism in a superalloy

A novel grain refiner composed of nickel,tungsten and yttria was prepared by the powder metallurgy way. The microstructure of the refiner alloy was studied by optical microscope(OM),scanning electron microscope(SEM) and energy dispersive spec-troscopy(EDS). The refinement process was simplized. It was shown that the alloy grains could be refined by addition of the refiners apparently even at high pouring temperature. The average grain size of the refiner free alloy was 4 mm,and 0.4 mm for the refined alloy. The fine-grain superalloy has excellent mechanical properties at intermediate temperature. The refinement mechanism was discussed.     

浆料制备工艺对Al-17Si-4Cu-0.5Mg合金组织性能的影响

研究了浆料制备工艺对和浇注温度对Al-17Si-4Cu-0.5Mg合金显微组织及力学性能的影响。结果表明,经电磁搅拌后,合金中的Si相发生钝化,但出现了聚集现象。超声振动处理后合金中的初生Si尺寸减小,形貌由树枝状转变为近球形。Si相颗粒数量为460个/mm²,圆整度为0.64,平均晶粒尺寸为15.7μm。当浆料浇注温度从620℃降到600℃时,合金组织得到明显细化,继续降低浇注温度,晶粒长大,组织存在孔洞缺陷。浆料温度为600℃时,合金抗拉强度为194MPa,伸长率为2.60%,硬度(HB)为120.2,与580℃下浇注相比分别提高了10.23%、6.12%和16.83%。此时,合金断口处韧窝数量增多,解理平台尺寸减小。     

AM60B镁合金的MgCO3晶粒细化技术（英文）

研究以MgCO3作为AM60B镁合金晶粒细化剂的细化工艺参数对微观组织的影响,从而开发一种细化工艺,同时,讨论其相应的细化机理。结果表明,升高MgCO3的添加温度或升高浇铸温度有利于获得细晶组织;在790°C时添加,最佳的加入量为1.2%,延长在此温度的保温时间使晶粒尺寸增大;在790°C时加入1.2%MgCO3,随后保温10min浇铸,可使晶粒尺寸从未细化的348μm减小到69μm;MgCO3与熔体中的合金元素反应所形成的Al4C3颗粒是异质形核的基底;除异质形核机理外,聚集在生长前沿的Al4C3颗粒对晶体生长的阻碍是晶粒细化的另一原因。     

Effect of nano TiN/Ti refiner on as-cast and hot-working microstructure of commercial purity aluminum

A novel type nano TiN/Ti composite grain refiner (TiN/Ti refiner) was prepared by high energy ball milling, and its effect on as-cast and hot-working microstructure of commercial purity aluminum (pure Al) was investigated. The results show that TiN/Ti refiner exhibits excellent grain refining performances on pure Al. With an addition of 0.2% TiN/Ti refiner, the average grain size of pure Al decreases to 82 μm, which is smaller than that of pure Ti and Al–5Ti–1B master alloy as refiners. The microstructure of weld joint of pure Al with 0.1% TiN/Ti refiner is fine equiaxed grains and the hardness of weld joint is higher than that of the base metal. For pure Al with 40% cold deformation and recrystallization at 250 °C for 1.0 h, the grains of the sample added 0.1% Ti powder have an obvious grain growth behavior. In contrast, oriented grains caused by deformation have been eliminated, and there is no obvious grain growth in pure Al refined with 0.1% TiN/Ti refiner, indicating that nano TiN in the refiner inhibits the growth of grain during recrystallization.     

双超声场对A356半固态浆料凝固组织的影响

试验研究了双超声场中,施振温度和处理区域距离,对流经处理区的A356铝合金半固态浆料凝固组织的影响规律。结果表明,双超声场对凝固组织的细化、球化效果较好。浇注温度为630℃并施振所获得的金相组织晶粒最细小,球化最均匀。而随着施振温度升高,晶粒反而变得粗大。同时,由于超声波的衰减,当处理区域距离为5mm时,获得的组织最好。     

Melting purification process and refining effect of 5083 Al–Mg alloy

To improve the poor stability of casting process of Al alloy with high Mg content, which leads to poor final product quality, the melting purification process and the influences of the refiner on the microstructure and defect of 5083 alloy were studied. The results show that the optimized process for the rotary impeller degassing of 5083 alloy is as follows: a rotary speed of 250–400 r/min; a gas flow of 1.2–2.0 L/s, a refining time of 10–15 min. This optimized process can reduce the gas content in the solid alloy to 2×10^?3 mL/g or lower. Due to the addition of grain refiner, the cast microstructure of 5083 alloy is refined. The Al–5Ti–1B wire shows the best refining effect among all the refiners. The refining effect is improved with the increase of grain refiner addition amount. And the refinement effects become stable when Ti content reaches 0.1% or higher. The surface crinkling defect of the billet can be easily found in the alloy refined with Al–5Ti–1B wire compared with the alloys refined with other refiners.     

TiN/Ti复合细化剂对工业纯铝细化效果的影响

利用高能球磨制备了一种金属钛包覆纳米TiN的复合晶粒细化剂(TiN/Ti),研究了该细化剂对工业纯铝的细化效果及其抗衰退性能.结果表明,TiN/Ti复合细化剂对工业纯铝具有良好的晶粒细化效果,当加入量仅为0.025％时,试样组织由粗大的柱状晶转变为等轴晶;当加入量为0.2％时,纯铝的晶粒平均尺寸为82μm.该细化剂在725℃铝液中保温30、60和120 min后,试样的晶粒尺寸分别为101、153和327 μm.相对纯钛粉,TiN/Ti细化剂表现出良好的抗衰退性能,其抗衰退性来源于金属钛包覆纳米TiN在铝液中的分散性和稳定性.     

NixAlyTiz添加剂对K4169高温合金铸态晶粒组织的影响

选用Ｋ４１６９Ｆｅ－Ｎｉ基高温合金,研究了向熔体中加入ＮｉｘＡｌｙＴｉｚ金属间化合物合金冷凝后的晶粒尺寸,枝晶组织等凝固组织特征的影响。结果表明,加入微量ＮｉｘＡｌｙＴｉｚ细化剂并控制合金液的均匀化处理过程可显著细化晶粒,将铸件整体晶粒细化至０．１－０．２ｍｍ,达到ＡＳＴＭ１－３级。同时,枝晶组织出现了由枝枝晶向胞状晶的转变,并且ＮｉｘＡｌｙＴｉｚ细化剂的加入对合金的结晶特性及凝固组织无不良影响。     

原位反应法制备Al-Ti-B-RE晶粒细化剂及其细化效果

以K2TiF6、KBF4、Al-10RE为添加物,采用原位反应法制备了Al-Ti-B-RE中间合金,通过正交法优化出各合金元素的合理配比,即5%Ti、1%B、0.5%RE,Ti元素的吸收率达92.4%。RE元素进入TiAl3相,阻碍其生长,TiAl3相以小块状为主,分布较均匀,增强细化效果。利用该细化剂对A356铝合金进行细化处理,其晶粒尺寸仅为经Al-5Ti-B处理过的晶粒的42.2%,枝晶间距明显缩小。