Cu对Al-Li合金组织结构与性能的影响

EFFECT OF Cu ON MICROSTRUCTURE AND PROPERTIES OF Al-Li ALLOYS

本文研究了3种Cu/Li比的Al-Li-Cu-Zr合金的时效析出组织及其性能。结果表明,实验合金时效由两级硬化过程所组成,其中第一级硬化是δ′相(3号合金为δ′+T_1相)强化而引起;第二级硬化是由于δ′+T_1(3号合金为δ′+T_1+θ′)的复合强化作用。当T_1相板条与δ′相颗粒相遇时,δ′相逐渐被T_1相吞并。Cu/Li比增加,合金的强(硬)度上升,但塑性下降,拉伸断口由穿晶变为沿晶形式,这与高Cu/Li比合金中晶界析出平衡相有关。

The aging precipitation structure and its properties of the Al-Li-Cu-Zr alloys with 3 different Cu/Li ratios have been studied. Experimental resultsshow that the aging hardening of the alloys consists of two steps: the first is stre-ngthened by δ'-phase (δ'+T_1 phase in alloy No.3), and the second by δ'+T_1 phase(δ'+T_1+θ' phase in alloy No.3). The plate of T_1-phase can absorb the Li atomsfrom δ' particles when the plate bumped into δ'-phase, and therefore, these δ' pha-se particles become smaller and gradually disappear. The strength and hardness areincreased with the increase of Cu/Li ratio which cuased a decrease in plasticity.The crack mode would change from transgranular to intergranular. This is due to theprecipitation of the equilibrium phases contained Cu at grain boundaries.