铜添加对近共晶Al-Si-xCu合金的微观组织和硬度的影响(英文)

研究铜含量对Al-Si-xCu(x=2%,3%,4%and5%)合金的微观组织和硬度的影响。不同铜含量的铝合金经熔炼后于690°C铸造成湿砂模并固化,于500°C保温7h进行固溶处理后对样品进行水冷。随后于190°C进行时效处理,分别保温5,10和15h,研究时效时间对基体硬度的影响。采用差热分析法,在冷却速度30K/min下确定平衡相的转变温度,并研究铜含量对四元共晶合金的形成和α(Al)+Si熔点的影响。结果表明,随着铜含量的增加,发生析出硬化从而导致基体硬度增加,α(Al)+Si的熔点降低,共晶相的含量增加。当铜含量超过2%时,生成熔点为507°C的四元共晶相。

A review:Past,present and future of grain refining of magnesium castings

Magnesium is the lightest constructional metal,which makes it an important material for different applications like automotive,transportation,aviation and aerospace.There are several studies about developing properties of existing Mg alloys and introducing new alloy systems to industrial producers.An important way to improve properties of metallic materials is to decrease grain size that results almost in increasing all kind of properties of the material.This review paper aims to summarize the literature about grain refining of magnesium alloys.The text is consisting of three sections,which focused on the(1)grain refining methods used in the past,which are not used today,(2)grain refining methods currently being used in the industry and(3)novel and newly developed methods that may find usage in the industry in future.Before explaining grain refining methods of magnesium alloys a general summary about grain refinement of metals is also provided.

Characterization of Cu–Ti powder metallurgical materials

Powder metallurgical Cu-Ti alloys with different titanium additions produced by hot pressing were characterized by optical microscopy, scanning electron microscopy, X-ray diffraction analysis, and hardness, wear and bending tests. The addition of titanium to copper caused the formation of different intermetallic layers around titanium particles. The titanium content of the intermetallics decreased from the center of the particle to the copper matrix. The hardness, wear resistance, and bending strength of the materials increased with increasing Ti content, whereas strain in the bending test decreased. Worn surface analyses showed that different wear mechanisms were active during the wear test of specimens with different chemical compositions. Changes in the properties of the materials with titanium addition were explained by the high hardness of different Cu-Ti intermetallic phases.

Effect of Si addition on microstructure and wear properties of Mg-Sn as-cast alloys

Effect of Si addition on microstructure,hardness and wear resistance of as cast Mg-5Sn and Mg-10Sn alloys were investigated.For this purpose alloys with wt.-%0,0.5,1,1.5 Si were cast using an induction furnace.Addition of Si to both alloys caused an increasement in the amount of intermetallic phases at the grain boundaries.Also refined grain structure was reported with increasing Si content in the cast alloys.Both increased amount of intermetallics and decreased grain size caused an increase in the hardness of the alloys.Wear resistance of the binary alloys first increased with Si addition and then decreased.Increased amounts of Si in the alloys caused crack formation during wear tests and decreased wear resistance.Sliding speed also has a dramatical effect on the wear resistance of the alloys.Increased sliding speed resulted with higher wear resistance.Worn surfaces of the alloys also investigated under scanning electron microscope to understand the wear mechanisms operated during wear tests.

热处理条件对Al4Cu2Ni2Mg合金组织和磨损性能的影响(英文)

Al4Cu2Ni2Mg合金是一种可时效硬化合金。研究不同固溶和时效热处理工艺参数对Al4Cu2Ni2Mg合金显微组织、硬度和耐磨性能的影响。采用光学显微镜和扫描电镜对样品的显微组织进行表征。通过硬度测试和磨损试验研究热处理工艺对材料性能的影响。结果表明,合金经过8h时效后,硬度值从未经时效处理的HV1096.5增加到HV10151.1,继续延长时效时间会导致合金的硬度值下降。随着合金硬度的提高,其耐磨性能得到提升。综合实验结果表明,在540°C固溶处理8h,然后在190°C时效处理8h,为该合金的最优热处理条件。