(沈陽工業(yè)大學(xué) 材料科學(xué)與工程學(xué)院，沈陽 110870)
摘 要: 采用拉伸試驗、電鏡觀察和晶間腐蝕(IGC)試驗，研究回歸再時效(RRA)處理對噴射成形7075合金組織形貌、力學(xué)性能和晶間腐蝕性能的影響，并與T6峰值時效、T73過時效進(jìn)行對比分析。結(jié)果表明：經(jīng)T6處理后，晶內(nèi)大量細(xì)小彌散的η′相使合金的抗拉強度達(dá)到760 MPa，但晶界處連續(xù)分布的η相和窄小的晶界無析出帶(PFZ)使合金抗晶間腐蝕性能變差，晶間腐蝕深度達(dá)131.4 μm；經(jīng)T73處理后晶界η相斷開及PFZ大幅增寬可改善合金的耐蝕性，晶間腐蝕深度僅為2.0 μm，但晶內(nèi)η′相粗化及體積分?jǐn)?shù)的減小使合金抗拉強度大幅下降，僅為676 MPa；采用(120 ℃，24 h)+(200 ℃，10 min)+(120 ℃，24 h)的RRA處理后合金晶內(nèi)η′相再次大量析出，致使抗拉強度達(dá)758 MPa，略低于T6態(tài)的抗拉強度，而晶界處斷續(xù)分布的η相和寬度略增的PFZ使合金抗晶間腐蝕性能也顯著改善，晶間腐蝕深度為16.8 μm，與經(jīng)T73處理后的接近。
關(guān)鍵字: 7075合金；噴射成形；回歸再時效；晶間腐蝕；顯微組織
（School of Materials Science and Engineering, Shenyang University of Technology, Shenyang 110870, China）
Abstract:The microstructure, mechanical properties and intergranular corrosion (IGC) behavior of spraying forming 7075 alloy undergone retrogression and re-aging (RRA) were studied by tensile test, electron microscopy, and IGC test, and compared with those of T6 peak aging and T73 overaging treatments. The results show that after T6 treatment, abundance transgranular dispersive η′ phases make the tensile strength of the alloy reach 760 MPa, continuous η phases at grain boundaries and narrow precipitate free zones (PFZ) make the IGC resistance decrease and IGC depth reach 131.4 μm. After T73 treatment, interrupted η phases at grain boundaries and wide PFZ can improve IGC resistance, and the IGC depth is only 2.0 μm, but depressed volume fraction of coarsening transgranular η′ phases greatly reduces the tensile strength of alloy to 676 MPa. After RRA treatment of (120 ℃, 24 h)+(200 ℃, 10 min)+(120 ℃, 24 h), abundance transgranular dispersive η′ phases separate out again, η phases at grain boundaries interrupt, and PFZ widen slightly. The tensile strength of alloy is 758 MPa, which is a little less than the strength after T6 treatment. IGC depth is 16.8 μm, which is close to that of the T73 treatment.
Key words: 7075 alloy; spray forming; retrogression and re-aging; intergranular corrosion; microstructure
