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Hereditary Effect of the Structure of the Charge on Density, Gas Content, and Processes of Solidification of an Al–Si–Cu Alloy System
Russian Journal of Non-Ferrous Metals ( IF 0.6 ) Pub Date : 2020-07-06 , DOI: 10.3103/s1067821220030104
K. V. Nikitin , V. I. Nikitin , I. Yu. Timoshkin

Abstract

The effect of the structure of the initial charge density in liquid and solid states, as well as on the temperature–time parameters of the process of solidification of the AK6M2 alloy (Al–6% Si–2% Cu), is shown. To obtain a coarse-crystal charge (C charge), part of the melt is crystallized in ceramic forms in a sand backfill with a cooling rate of ~0.5–1.0°C/s. The fine-crystal charge (F charge) in the form of thin ingots weighing 0.2–0.3 kg is obtained by crystallization of the melt in cast-iron cold molds with ~5.0–10°C/s. Further, the charge billets are separately melted, re-refined and degassed, and the samples are poured to determine the gas content and density in the liquid (dL) and solid (dS) states. It is established that structural information from the original charge of the alloy is stable in the solid–liquid–solid system. Direct thermal analysis is used to find that the melt obtained from the F charge hardens at low temperatures: the decrease in liquidus temperature tL is 3°C; the temperature of the beginning of solidification of the eutectic is reduced by 10°C, and the temperature of the end of solidification of a eutectic is 3°C in comparison with the melt of the C charge. At the same time, the formation of α-Al and eutectic dendrites in the melt from the F charge occurs 0.4 and 0.6 min more quickly, respectively. The results obtained on the Paraboloid-4 installation show that a smaller number of pulses throughout the studied temperature range passes through the melt from the F charge, which confirms its increased density when compared to the alloy from the C charge. Thus, for the melt from the F charge, the values of the degrees of compaction were –ΔJl ~ 278.66 and –ΔJe ~ 129.83 imp/s and, for the melt from the C charge, –ΔJl ~ 302.9 and –ΔJe ~ 163.47 imp/s. The values of the phase-transition temperatures determined by anomalies on the temperature dependence Jt practically coincide with the results of direct thermal analysis. The main technological recommendations of management by structural information in aluminum alloys are formulated from the position of the phenomenon of structural heredity.


中文翻译:

装料结构对Al-Si-Cu合金体系的密度,气体含量和凝固过程的遗传影响

摘要

显示了液态和固态初始电荷密度的结构,以及对AK6M2合金(Al–6%Si–2%Cu)的凝固过程的温度-时间参数的影响。为了获得粗晶电荷(C电荷),部分熔体在回填砂中以陶瓷形式结晶,冷却速率为〜0.5–1.0°C / s。通过在铸铁冷模中以约5.0–10°C / s的速度结晶熔体,可以得到重量为0.2–0.3 kg的细锭形式的细晶电荷(F电荷)。此外,将装料坯分别熔化,重新精炼和脱气,然后倒入样品以确定液体(d L)和固体(d S)中的气体含量和密度) 状态。已经确定,来自合金原始装料的结构信息在固液固系统中是稳定的。通过直接热分析发现从F装料中获得的熔体在低温下会硬化:液相线温度t L的降低是3°C;与C装料的熔融相比,共晶的凝固开始的温度降低了10℃,并且共晶的凝固结束的温度为3℃。同时,由F装料在熔体中形成α-Al和共晶树枝状晶体的速度分别加快了0.4和0.6分钟。在抛物面-4安装表明脉冲的整个研究的温度范围内的较少数量的经过从F电荷,相对于从该合金时确认其密度增加熔体获得的结果Ç电荷。因此,对于从F电荷熔体中,度压实的值分别为-Δ Ĵ〜278.66和-Δ Ĵ Ë〜129.83小鬼/ s和,对于从C充电,-Δ熔融Ĵ〜302.9和-Δ Ĵ ë〜163.47小鬼/秒。由温度依赖性Jt的异常确定的相变温度值实际上与直接热分析的结果一致。铝合金结构信息管理的主要技术建议是从结构遗传现象的位置提出的。
更新日期:2020-07-06
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