Nano-sized dispersoids formed by solid state reactions in mechanically alloyed aluminum based materials

用三种不同的原料：(1)预合金锭粉末、(2)纯元素混合粉末和(3)添加合金元素氧化物的纯铝粉，对Al-Fe和Al-Mn系进行了机械合金化。采用真空热压和热挤压相结合的方法将机械合金化粉末与粉末冶金材料结合。对粉末冶金材料的组织和力学性能进行了测试。结果表明，在机械合金化过程中或机械合金化处理后，通过氧的置换反应原位获得Al_2O_3和Al_2O_3化合物的弥散，添加氧化物是获得性能优良材料的有效途径。在Al-Cr系、Al-Hf系、Al-Mo系、Al-Ti系、Al-W系、Al-Zr系中加入合金元素氧化物制备了机械合金化材料。X-射线衍射分析表明，添加的氧化物发生分解，生成Al_2O_3和铝化物化合物…在这些材料中有更多信息。众所周知，这些铝合金系统很难用熔炼和铸造的方法制备，因为铝和滑石元素的密度和熔点有很大的差异。已证实，添加合金元素氧化物的机械合金化是这类合金系的有效合金化方法。由于这些材料中分散体的形成是通过固相反应进行的，所以分散体的数量和平均尺寸比在液态反应中更容易控制。因此，添加氧化物能够在机械合金化的铝基材料中通过固相反应获得纳米级的分散体。当固结材料在很高的温度下(如773或873K)加热时，许多材料的硬度都随着固相反应的进行而增加。在铝钼系中，当热挤压材料在873K下加热40K时，其硬度增加幅度最大。这些合金系统的大部分挤压后材料的抗拉强度都在500 MPa以上，表明机械合金化材料中氧的固态置换反应形成的弥散体对铝基材料的强化是有效的。较少

Mechanically alloying was carried out for the Al-Fe and Al-Mn systems from three different starting materials : (1) powders from prealloyed ingots, (2) mixed powders of pure elements and (3) pure aluminum powder with addition of oxides of alloying elements. Mechanically alloyed powders were consolidated to the P/M materials by vacuum hot pressing and hot extrusion. Structures and mechanical properties were examined on the P/M materials. It has been shown that oxide addition is an effective way to obtain materials of superior mechanical performance since dispersion of Al_2O_3 and aluminide compounds is obtained in situ by the displacement reaction of oxygen during or after mechanical alloying treatment. Furthermore, mechanically alloyed materials were produced in the Al-Cr, Al-Hf, AL-Mo, Al-Ti, Al-W, Al-Zr systems by adding the oxide of alloying elements to aluminum powder. X-ray diffraction revealed that the added oxides were discomposed and Al_2O_3 and aluminide compounds were formed … More in these materials. These aluminum alloy systems are known to be difficult to prepare by the melting and casting method because of significant differences in the density and melting point between aluminum nd slloying elements. It has been confirmed that mechanical alloying with additon of the oxides of alloying elements is an effective alloying method for such alloy systems. Since formation of dispersoids in these materials occurs by solid state reactions, the amount and average size of dispersoids can be more easily controlled than in the liquid state reactions. Thus, oxide addition enables to obtain nano-sized dispersoids formed by solid state reactions in mechanically alloyed aluminum based materials. Hardness increases were observed in many of these materials with the progress of such solid state reactions when consolidated materials were heated at very high temperatures such as 773 or 873K.The highest hardness increase of HV75 was observed in Al-Mo system when its hot-extruded material was heated at 873K for 40ks. Most of the as-extruded materials of these alloy systems showed high tensile strength above 500MPa, and thus dispersoids formed by solid state displacement ractions of oxygen in mechanically alloyed materials are shown to be effective for strengthening aluminum based materials. Less