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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.

核心粒子组成的复合沉淀,大概Al (Li Ti)和delta-Al_3Li阶段的外壳是由两级老化(500゚C,然后在180年或190年゚C)在寒冷的标本Al - (1.6 - -2.3) wt % Li - (0.45 - -0.95) wt % Ti合金,Al-Li-Ti三元合金含有复合沉淀和粒子peak-aged条件,表现出相当优越的延性的peak-aged铝锂二元合金与更高的强度。含复合析出相的Al-Li-Ti合金拉伸应变试样在复合析出相附近观察到弓形位错和缠结位错，SEM断口观察到剪切型穿晶断裂。另一方面，在Al-Li二元合金峰时效试样中观察到位错的平面滑移和典型的晶间断裂。复合析出相通过延缓Al-Li-Ti合金的平面滑移模式来提高塑性。研究了al - 20wt % Ti混合粉末在磨耗器式球磨机机械合金化过程中非相相的形成和硬化过程。结果表明：机械合金化过程中出现了片状成形、片状粉末的冷焊、复合粉末的断裂、固溶体和非晶相的形成。从钛的固溶硬化、Al_2O_3的分散硬化、加工硬化和铝晶粒细化硬化等方面解释了混合粉末在MA过程中硬度的显著提高。