喷射沉积连续挤压高硅铝合金的组织与性能研究
发布时间：2018-09-06 16:38
【摘要】：高硅铝合金具有质量轻、硬度高、耐磨性好,热膨胀系数低等优点而被广泛应用于汽车、航空和电子工业中。传统铸造高硅铝合金中粗大的初晶硅相和富铁相会割裂铝基体,严重影响合金的韧塑性及加工性能。喷射沉积连续挤压(Spray Conform,简称SC)是新近提出的一种材料加工新技术,兼有喷射沉积和连续挤压两种技术的优点,可连续成形具有快速凝固组织的管棒型线材。该技术的出现可望为高硅铝合金的高效低成本制备提供一条新的途径。本文采用SC法制备了七种高硅铝合金,研究了合金的微观组织、力学性能和磨损性能。为解决喷射沉积区域较宽,而连续挤压机轮槽较窄的技术问题,研制了双旋转盘流型控制器以约束雾化射流。研究了雾化气体压力和熔液温度对约束喷射铝硅合金沉积坯形貌及微观组织的影响,并结合人工神经网络模型,获得了喷射沉积阶段的优化参数。基于X射线分析技术研究了 Fe含量对SC态合金中α-A1晶格常数的影响,发现Fe含量越高,α-A1晶格畸变越大,晶格常数越大。探讨了 SC态合金中富铁相的形成机制,发现沉积阶段雾滴的冲击和连续挤压过程中的剧烈剪切是形成细小富铁相的主要原因。研究了挤压比对SC法制备的Al-20Si合金组织及性能的影响。发现随挤压比的增加,初晶硅相的尺寸不断减小,且形状更为规整。挤压比较高时,合金具有较高的硬度、强度和耐磨性。当挤压比达到20时,可获得初晶硅相细小(等效直径约3.3 μ m)均匀且完全致密的合金材料。SC法制备的Al-xSi(x=20,25,30 wt.%)合金中的初晶Si相细小且圆整,尺寸仅为铸态合金的1/20。较高的硅含量形成更大体积分数的细小硅颗粒,产生更明显的第二相强化,致使合金强度随Si含量的增加而不断升高。相对于同等硅含量的铸态合金,SC态合金的强度、塑性和耐磨性均有明显提升,且硅含量越高,效果越明显。SC法制备的Al-20Si-xFe(x=2,3,4,5 wt.%)合金中的第二相主要由细小的硅颗粒、短棒状δ相和短针状p相构成。相对于铸态合金,Si颗粒等效直径下降了1个数量级,富铁相的尺寸下降1～2个数量级。SC态Al-20Si-xFe合金内的第二相尺寸细小且分布均匀,较高的铁含量会形成更大体积分数的第二相,产生更明显的强化效果。使得Al-20Si-xFe合金的强度随Fe含量的增加而不断升高,当Fe含量为5%时,抗拉强度可达367MPa。相对于同等铁含量的铸态合金,SC态合金的强度、塑性和耐磨性均有明显提升,且铁含量越高,增幅越大。SC态Al-20Si-xFe合金的高温(200℃)强度较室温强度有所下降,而塑性却有明显提升。高温强度随Fe含量的增加不断升高,当Fe含量为5%时,抗拉强度可达到192MPa。SC态Al-20Si-xFe合金具有优良的室温和高温(200℃)耐磨性能,当Fe含量为4%时,高温磨损率仅为3.8× 10-10g/(N · mm)。
[Abstract]:High silicon aluminum alloy is widely used in automobile, aviation and electronic industry because of its advantages of light weight, high hardness, good wear resistance and low thermal expansion coefficient. The coarse primary silicon phase and iron rich phase in conventional casting high silicon aluminum alloy will split the aluminum matrix, which seriously affects the ductility and processing properties of the alloy. Spray deposition continuous extrusion (Spray Conform,) is a new material processing technology proposed recently. It has the advantages of both spray deposition and continuous extrusion. This technology is expected to provide a new way for the high-efficiency and low-cost preparation of high-silicon aluminum alloy. Seven kinds of high silicon aluminum alloys were prepared by SC method. The microstructure, mechanical properties and wear properties of the alloys were studied. In order to solve the technical problem that the spray deposition area is wider and the wheel slot of the continuous extruder is narrow, a dual rotating disk flow pattern controller is developed to constrain the atomization jet. The effects of atomization gas pressure and melt temperature on the morphology and microstructure of the confined spray Al-Si alloy deposition billet were studied. The optimized parameters of spray deposition stage were obtained by combining the artificial neural network model. The effect of Fe content on the lattice constant of 伪 -A1 in SC alloy was studied based on X-ray analysis. It was found that the higher the content of Fe, the greater the lattice distortion and the larger the lattice constant of 伪 -A1. The formation mechanism of Fe-rich phase in SC alloy was discussed. It was found that the main reasons for the formation of fine Fe-rich phase were the impact of droplets during deposition and the intense shear during continuous extrusion. The effect of extrusion ratio on the microstructure and properties of Al-20Si alloy prepared by SC method was studied. It is found that with the increase of extrusion ratio, the size of primary silicon phase decreases and the shape is more regular. When extrusion is high, the alloy has higher hardness, strength and wear resistance. When the extrusion ratio reaches 20:00, the primary Si phase in the Al-xSi (xF20) 2530 wt.% alloy prepared by SC method with fine primary silicon phase (equivalent diameter about 3.3 渭 m) is obtained. The size of the alloy is only 1 / 20 of that of the as-cast alloy. The higher the silicon content is, the larger the volume fraction of the fine silicon particles is, and the more obvious the second phase strengthening is, and the strength of the alloy increases with the increase of Si content. Compared with the as-cast alloy with the same silicon content, the ductility and wear resistance of the cast SC alloy are obviously improved, and the higher the silicon content is, the more obvious the effect is. The second phase of the Al-20Si-xFe alloy prepared by the SC method is mainly composed of fine silicon particles, the second phase of which is mainly composed of fine silicon particles, and the second phase of the alloy is mainly composed of fine silicon particles, and the second phase of the alloy is mainly composed of fine silicon particles. The short rod 未 phase and the short needle p phase are formed. Compared with the as-cast alloy, the equivalent diameter of Si particles decreases by 1 order of magnitude, and the size of rich iron phase decreases by 1 ~ 2 orders of magnitude. The size of the second phase in Al-20Si-xFe alloy is small and uniform. Higher iron content will form a second phase with a larger volume fraction, resulting in a more obvious strengthening effect. The strength of Al-20Si-xFe alloy increases with the increase of Fe content. When the content of Fe is 5, the tensile strength can reach 367 MPA. Compared with the as-cast alloy with the same iron content, the ductility and wear resistance of the cast alloy SC have been obviously improved, and the higher the iron content, the higher the increase of the strength of the Al-20Si-xFe alloy at high temperature (200 鈩，
本文编号：2226929
[Abstract]:High silicon aluminum alloy is widely used in automobile, aviation and electronic industry because of its advantages of light weight, high hardness, good wear resistance and low thermal expansion coefficient. The coarse primary silicon phase and iron rich phase in conventional casting high silicon aluminum alloy will split the aluminum matrix, which seriously affects the ductility and processing properties of the alloy. Spray deposition continuous extrusion (Spray Conform,) is a new material processing technology proposed recently. It has the advantages of both spray deposition and continuous extrusion. This technology is expected to provide a new way for the high-efficiency and low-cost preparation of high-silicon aluminum alloy. Seven kinds of high silicon aluminum alloys were prepared by SC method. The microstructure, mechanical properties and wear properties of the alloys were studied. In order to solve the technical problem that the spray deposition area is wider and the wheel slot of the continuous extruder is narrow, a dual rotating disk flow pattern controller is developed to constrain the atomization jet. The effects of atomization gas pressure and melt temperature on the morphology and microstructure of the confined spray Al-Si alloy deposition billet were studied. The optimized parameters of spray deposition stage were obtained by combining the artificial neural network model. The effect of Fe content on the lattice constant of 伪 -A1 in SC alloy was studied based on X-ray analysis. It was found that the higher the content of Fe, the greater the lattice distortion and the larger the lattice constant of 伪 -A1. The formation mechanism of Fe-rich phase in SC alloy was discussed. It was found that the main reasons for the formation of fine Fe-rich phase were the impact of droplets during deposition and the intense shear during continuous extrusion. The effect of extrusion ratio on the microstructure and properties of Al-20Si alloy prepared by SC method was studied. It is found that with the increase of extrusion ratio, the size of primary silicon phase decreases and the shape is more regular. When extrusion is high, the alloy has higher hardness, strength and wear resistance. When the extrusion ratio reaches 20:00, the primary Si phase in the Al-xSi (xF20) 2530 wt.% alloy prepared by SC method with fine primary silicon phase (equivalent diameter about 3.3 渭 m) is obtained. The size of the alloy is only 1 / 20 of that of the as-cast alloy. The higher the silicon content is, the larger the volume fraction of the fine silicon particles is, and the more obvious the second phase strengthening is, and the strength of the alloy increases with the increase of Si content. Compared with the as-cast alloy with the same silicon content, the ductility and wear resistance of the cast SC alloy are obviously improved, and the higher the silicon content is, the more obvious the effect is. The second phase of the Al-20Si-xFe alloy prepared by the SC method is mainly composed of fine silicon particles, the second phase of which is mainly composed of fine silicon particles, and the second phase of the alloy is mainly composed of fine silicon particles, and the second phase of the alloy is mainly composed of fine silicon particles. The short rod 未 phase and the short needle p phase are formed. Compared with the as-cast alloy, the equivalent diameter of Si particles decreases by 1 order of magnitude, and the size of rich iron phase decreases by 1 ~ 2 orders of magnitude. The size of the second phase in Al-20Si-xFe alloy is small and uniform. Higher iron content will form a second phase with a larger volume fraction, resulting in a more obvious strengthening effect. The strength of Al-20Si-xFe alloy increases with the increase of Fe content. When the content of Fe is 5, the tensile strength can reach 367 MPA. Compared with the as-cast alloy with the same iron content, the ductility and wear resistance of the cast alloy SC have been obviously improved, and the higher the iron content, the higher the increase of the strength of the Al-20Si-xFe alloy at high temperature (200 鈩，
本文编号：2226929
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