用机械合金化工艺制造弥散强化Al-C合金
来源期刊:中南大学学报(自然科学版)1985年第1期
论文作者:邱光汉 黄泽培 阮建民 孙友章
文章页码:47 - 55
关键词:弥散强化; 机械合金化; 合金粉末; 合金化工艺; 机械性能; 化学稳定性; 烧结铝; 物理; 高温性能; 拉伸强度
摘 要:高能球磨纯铝粉和碳,然后把处理好的粉末热挤压密实,制得了弥散强化Al-C合金。本研究工作采用并比较了两种添加碳的方法——物理碳法和化学碳法。结果表明,两种方法都能得到很好的室温和高温性能,而且强度水平达到和超过SAP铝合金。化学碳法对性能的影响明显地优于物理碳法,但是添加物理碳对合金粉末的安全操作是有利的,同时组份可以得到精确的控制。本文简要地叙述了粉末锻造工艺,除塑性差外锻造制品的其他机械性能也是良好的,特别是对添加化学碳的合金。
Abstract: Dispersion-strengthening Al-C alloys have been prepared by mechanical alloying technology. Its technological process was as follows: high energy milling of pure aluminium powder with carbon black or organic agents, cold isostatic compacting of the milled powder at 2—2.5 t/cm2, packing the green compacts with pure aluminium sheet without scaling, heating the compacts to 550-600℃ in nitrogen atmosphere for 1 hr., and final hot extrusion consolidation to obtain extruded bars of diameter 13mm with reduction ratio of 26:1. In the present work, two methods of addition of carbon were used and compared: physical carbon method, in which carbon black was adoped directly; chemical carbon method, in which carbon was created through the decomposition of organic agents, such as stearic acid or methanol during milling or subsequent heat treatment. The experiment results showed that both the methods of carbon addition could achieve excellent mechanical properties at normal or elevated temperature, and the strength levels could reach or surpass those of coventionally produced SAP aluminium alloys. The tensile properties of the extruded bar with chemical 1.23 w.t% carbon at room temperature were σb 42—43 kg/mm2(412—422 MN/m2), δ 5—8%, ψ 18—21%, and that with physical 3wt.%carbon, σb 37—39 kg/mm2 (363—382MN/m2), σ 8—10%, ψ13—17%. It is evident that the effect of chemical carbon on mechanical properties is considerably better than that of physical carbon, which might be contributed to a more fine and more uniform distribution of dispersoids. But the addition of physical carbon is beneficial to the safety in operating of the milled powder, and the elemental composition can be accurately controlled. The technology of powder forging was also described briefly. In order to reduce the cold work hardening of milled powder and create in-situ Al2O3 and Al4C3 dispersoids, the milled powder was annealed in nitrogen atmo- sphere at 550—600℃ for 1 hr., and then the softened powder was die pressed into preforms of 9.2mm (width)×67.9mm(length) at 3—3.5t/cm2, and finally the preforms were heated in dissociated ammonia at 600℃ and forged in a 60t frictional press to obtain billets of 12.6mm×70.2mm. The forging products, especially alloy with the addition of chemical carbon, possess good mechanical properties except low ductility, for example, the alloy containing chemical 0.99 wt.% carbon was σb 35—37kg/mm2 (343—363MN/m2), the elevated temparature tensile strength at 300 and 400℃ was 26—27kg/mm2(255—265MN/m2) and 19—20 kg/mm2(186—196MN/m2) respectively.