Composite precipitation and improvement of ductility in Al-Li-Ti alloys

Al-Li-Ti 合金中的复合析出和延展性改善

基本信息

批准号：
63550538
负责人：
SAJI Shigeoki
金额：
$ 1.15万
依托单位：
Osaka University
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (C)
财政年份：
1988
资助国家：
日本
起止时间：
1988 至 1989
项目状态：
已结题

项目摘要

Composite precipitates consisting of the core particle,presumably Al (Li, Ti) and the outer shell of delta-Al_3Li phase were formed by a two-stage aging ( at 500ﾟC and then at 180 or 190ﾟC) in chill cast specimens of Al-(1.6-2.3)wt% Li-(0.45-0.95)wt%Ti alloys, Al-Li-Ti ternary alloys containing both the composite precipitates and particles in the peak-aged condition, showed a considerably superior ductility to that of the peak-aged Al-Li binary alloy together with a higher strength. Bow-out dislocations and tangled dislocations were observed near the composite precipitates in the tensile-strained specimens of Al-Li-Ti alloys containing the composite precipitates and shear type of transgranular fracture were recognized in SEM fractografy. On the other hand, planar slip of dislocations and typical intergranular fracture were observed in the peak-aged specimens of Al-Li binary alloys. The composite precipitates improve ductility by retarding the planar slip mode in Al-Li-Ti alloys.Alloying processes, formation of amorphase phase and hardening of Al-20 wt% Ti mixed powders during mechanical alloying by Attritor type of ball mill, have been investigated. The following results were obtained: A mechanical alloying process of flake-forming, cold welding of the flaked powders, fracturing of the composite powders, forming of solid solution and amorphous phase was detected. Remarkable increase in hardness of the mixed powders during MA were explained in terms of solid solution hardening by titanium, dispersion hardening of Al_2O_3, work-hardening and hardening by refinement of crystal grains of aluminum.

通过两阶段时效（500°C，然后180或190°C）在冷铸样品中形成由核心颗粒（可能是Al（Li，Ti））和δ-Al_3Li相外壳组成的复合析出物Al-(1.6-2.3)wt% Li-(0.45-0.95)wt%Ti 合金、Al-Li-Ti在峰值时效条件下同时含有复合析出物和颗粒的三元合金表现出比峰值时效铝锂二元合金显着优越的延展性，并且在接近时效条件下观察到了更高的强度。另一方面，在SEM断口图中发现了含有复合析出物的Al-Li-Ti合金拉伸应变样品中的复合析出物和穿晶断裂的剪切类型。另一方面，在 Al-Li 二元合金的峰值时效样品中观察到位错的平面滑移和典型的晶间断裂，复合析出物通过延迟 Al-Li-Ti 合金中的平面滑移模式来提高延展性。合金化过程，无定形酶的形成。对采用球磨机进行机械合金化过程中 Al-20 wt% Ti 混合粉末的相和硬化进行了研究，得到了以下结果：机械合金化过程。检测到MA过程中混合粉末的片状形成、片状粉末的冷焊、复合粉末的断裂、固溶体和非晶相的形成，其硬度显着增加可以用钛固溶硬化、弥散硬化来解释。 Al_2O_3的加工硬化和细化铝晶粒的硬化。