研究了稀土镧和钇对过共晶铝硅合金的微观组织和力学性能的影响。实验合金为Al-22%Si，所加稀土为富镧混合稀土（含80%L a）和Al-88%Y中间合金，加入量分别为0.6%～1.4%L a和0.10%～0.18%Y。合金熔化精炼后在预热至250℃的金属型中浇铸成Φ12mm×60mm试棒，浇注温度740℃。高温力学性能测试300℃下保温30min后的拉伸强度。实验结果表明：单独加入稀土不能细化初晶硅，结合磷的作用，镧、钇可实现初晶硅和共晶硅的双重变质，其中初晶硅可细化至22Lm左右；适量La可形成有利于提高高温性能的Al5SiCu2La化合物；Y可以有效地抑制该化合物长成粗大针状。经淬火及稳定化回火热处理后，合金室温抗拉强度可达276MPa，高温强度可达174MPa。

针对材料产业的现状和发展趋势，提出了生态材料学的概念，即生态材料学是关于材料及材料循环过程与生态环境相互作用的科学，其目的在于使材料在满足所需性能的前提下，具有优良的生态环境协调性。分析了生态材料学的基本思想和主要研究内容，给出了环境负荷表达式和材料科学与工程的新判据。以铝合金熔体纯净化生态处理工艺为例，指出了材料科学与工程的发展方向。

Several methods using the concept of electromagnetic separation of nonmetallic inclusions from an aluminum melt were analytically studied and compared in this article. The migration rate of inclusion particles for each method by exerting different types of electromagnetic field, viz. DC electric field with steady magnetic field, AC magnetic field, and AC electric field, was calculated and compared with the gravity settling velocity. Effects of various operating parameters, such as the imposing time of electromagnetic field, the radius of circular pipe, and the magnitude of electromagnetic force, on inclusion removal efficiency were analyzed and illustrated for each case. It was found that the removal efficiency increases with the increase of imposing time and decreases dramatically with the increase of pipe radius, especially for the AC electric field method. As far as the removal of small inclusions is concerned, the AC magnetic field method is the most favorable one because it has the least dependence of removal efficiency upon the particle size. However, high frequency is needed in order to get the optimum results, and the best values of a/δ are in the range of 2 to 3.

Effects of secondary flow of the melt on the separation of inclusions from molten aluminum flowing in a square channel by a solenoid were investigated theoretically and experimentally. Numerical methods were used to calculate the secondary flow, the separation efficiency of inclusions, and the particle motion. It is found that there appear two recirculating loop flows in a quarter cross section of the channel and the separation efficiency of inclusions is significantly improved by the secondary flow mainly owing to the mixing effect. The separation efficiency increases with the increase of the effective magnetic flux density and the frequency of magnetic field, and decreases significantly with the increase of the size of the separator channel for a constant value of a/δ. However, it is possible to achieve high separation efficiency by using argesized square channels and high frequency magnetic field with the help of the mixing effect of secondary flow. The computed results of particle trajectories show that the secondary flow accelerates the transportation of the particles from the inner region to the vicinity of the wall and greatly shortens the separation time of those particles. The effects of secondary flow on the separation efficiency were confirmed by comparing the measured separation efficiency with the computed results.

A new refining method-melt thermal treatment without additive to melt is studied in this paper. Microstructure analysis and property evaluation of hypoeutectic Al-Si alloys treated with this method show that the solidification microstructure can be refined significantly with a considerable increase in elongation ratio and strength. Effects such as cooling rate, holding time and alloy composition on the solidification microstructure and mechanical properties have been evaluated. It is shown that the strengthening and toughening effects on the treated samples vary with alloy composition. The property increment of the alloy rich of iron is relatively more remarkable than those rich of Cu or Mg element. Specifically, the structure of the low temperature melt is identified as a primary factor, on which the solidification structure of the treated melt is dependent.