本文選題：-T鋁合金 + 顯微組織��； 參考：《機械工程材料》2017年07期

【摘要】：在不同應力幅下(60%σ_s,70%σ_s,80%σ_s,90%σ_s,σ_s為試驗合金屈服強度)對7075-T651鋁合金進行了應力控制下的疲勞試驗,研究了其循環(huán)應變響應,觀察了疲勞斷口形貌、表面損傷形貌以及顯微組織,分析了疲勞裂紋的萌生及擴展機制。結果表明:試驗合金中析出了微米級的Al7Cu2Fe顆粒、納米級的η′(MgZn2)相和尺寸較大的η(MgZn2)相,此外,還存在尺寸為3~10nm的細小球狀GP區(qū);在較高應力幅(80%σ_s,90%σ_s)控制下,試驗合金表現(xiàn)出先軟化后硬化直至斷裂的疲勞行為,而在較低應力幅(60%σ_s,70%σ_s)下則先軟化后明顯硬化并趨于穩(wěn)定;試驗合金主要發(fā)生微孔聚集韌窩型斷裂,在較高應力幅下,裂紋源位于粗大夾雜物Al7Cu2Fe和第二相MgZn2處,位錯大量纏結,而在低應力幅下,裂紋源位于基體輕微撕裂處,位錯形態(tài)為分散的短或長直位錯線。
[Abstract]:The fatigue tests of 7075-T651 aluminum alloy under stress control were carried out under different stress ranges (60% 蟽 _ S _ S _ (70%) 蟽 _ S _ S _ (80%) 蟽 _ s _ (90)% 蟽 _ S, 蟽 _ s as experimental alloy yield strength). The cyclic strain response of 7075-T651 aluminum alloy was studied, and the fatigue fracture morphology, surface damage morphology and microstructure were observed. The mechanism of fatigue crack initiation and propagation is analyzed. The results show that micrometer Al _ 7Cu _ 2FE particles, nanoscale 畏'(MgZn _ 2) and larger 畏 (MgZn _ 2) phases are precipitated in the test alloy, and there is a small globular GP region with the size of 3~10nm, which is controlled by a higher stress amplitude (80% 蟽 s ~ (90%) 蟽 ~ (2). The test alloy shows the fatigue behavior of softening and hardening before fracture, while at the lower stress amplitude (60% 蟽 / s, 70% 蟽 / s), the alloy softens and harms obviously and tends to stabilize, and the microporous aggregate dimple fracture occurs in the test alloy, and the fracture occurs at a higher stress amplitude. The crack source is located at the coarse inclusions Al _ 7Cu _ 2FE and the second phase MgZn _ 2, and there are a lot of dislocation entanglement. At the low stress amplitude, the crack source is located at the point where the matrix is slightly torn, and the dislocation morphology is a short or long straight dislocation line.
【作者單位】： 合肥工業(yè)大學材料科學與工程學院;合肥工業(yè)大學安徽省有色金屬材料與加工工程實驗室;
【基金】：國家自然科學基金資助項目(51201054) 國家51批博士后面上基金資助項目(2012M511400) 教育部博士點基金資助項目(20120111120030) 安徽省科技攻關計劃項目(1301021006)
【分類號】：TG146.21
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本文編號：2095805