(中南大學(xué) 材料科學(xué)與工程學(xué)院, 長沙 410083)
摘 要: 根據(jù)超高強鋁合金淬火、 時效組織透射電鏡觀察結(jié)果， 以及合金斷裂行為與斷口形貌分析， 提出了一種Al-Zn-Mg-Cu合金產(chǎn)生延性斷裂的物理模型。 對平衡相、 基體沉淀相、 無析出微區(qū)的斷裂行為進行了分析。 研究結(jié)果表明， 在晶內(nèi)同步變形條件下， 平衡相粒子最先斷裂； 晶內(nèi)沉淀區(qū)內(nèi)裂紋的形成與擴展早于無析出區(qū)， 沉淀區(qū)內(nèi)初始孔洞擴展與聚合， 導(dǎo)致沉淀區(qū)斷裂， 這是合金斷裂的主要原因； 無析出區(qū)最后斷裂。 引起淬火敏感性的平衡相粒子， 不是造成合金斷裂的直接原因， 粒子周圍的無析出微區(qū)起到了限制裂紋擴展和協(xié)調(diào)變形的作用， 是合金形成延性拉伸斷口的原因。
關(guān)鍵字: 鋁合金; 淬火; 平衡相; 斷裂; 無析出區(qū)
（ School of Materials Science and Engineering, Central South University, Changsha 410083, China）
Abstract: An intercrystalline ductile fracture physical model of ultra-high-strength Al-Zn-Mg-Cu alloy was given and the stage fracture behaviors of equilibrium phase, matrix precipitation and microzone of precipitate free zone (PFZ) were analyzed by TEM observation of the quenched and aged microstructures, the fracture behavior and morphology of Al-Zn-Mg-Cu alloy. The results show that under the synchro deformation circumstances, the equilibrium phase particles are fractured firstly, the formation and extension of fracture in intercrystalline precipitate zone are earlier than those in PFZ; the matrix precipitation is fractured due to the coaction between the primary cavities produced by equilibrium phase particles in precipitation zone and the secondary cavities produced by precipitation, this is the major fracture reason of the alloy; the precipitate free zone is fractured lastly. The equilibrium phase particles that induce the sensitivity of the quenching are not the direct reason that causes the alloy fracture; the microzone of PFZ around particles limits crack extension and coordinates deformation, this causes the formation of the ductile tension fracture.
Key words: aluminum alloy; quench; equilibrium phase; fracture; precipitate free zone
