(中南大學(xué) 材料科學(xué)與工程學(xué)院，長(zhǎng)沙 410083)
摘 要: 采用熱模鍛工藝制備了Mg-8.94Gd-1.80Y-0.42Zr-0.21Ag(質(zhì)量分?jǐn)?shù)，%)合金大型錐形殼體，對(duì)殼體不同部位的顯微組織與力學(xué)性能進(jìn)行了分析。結(jié)果表明：沿錐形殼體高度方向及壁厚方向的顯微組織均存在明顯差異，沿高度方向，錐形殼體頂層與中層比底層具有更高的再結(jié)晶程度；沿壁厚方向，由內(nèi)至外再結(jié)晶程度先降低后升高。頂層與中層的內(nèi)部均近乎發(fā)生完全動(dòng)態(tài)再結(jié)晶，而其余部位為粗晶、細(xì)晶構(gòu)成的混晶組織。錐形殼體頂層與底層部位均表現(xiàn)出明顯的力學(xué)性能各向異性，中層部位的力學(xué)性能則近乎各向同性，這與試樣不同晶體取向所導(dǎo)致的變形機(jī)制差異密切相關(guān)。合金經(jīng)時(shí)效處理后，強(qiáng)度得到顯著提高，力學(xué)性能各向異性程度降低，但室溫拉伸斷裂方式由韌性斷裂與脆性斷裂的混合斷裂方式轉(zhuǎn)變?yōu)閱我坏拇嘈詳嗔选?/span>
關(guān)鍵字: 鎂合金；模鍛；顯微組織；力學(xué)性能；時(shí)效處理
（School of Materials Science and Engineering, Central South University, Changsha 410083, China）
Abstract:The microstructure and mechanical properties of different parts of the Mg-8.94Gd-1.80Y-0.42Zr-0.21Ag (mass fraction, %) alloy large conical shell prepared by the hot die forging process were analyzed. The results show that there are obvious differences in microstructure along the height direction and thickness direction of the conical shell. Along the height direction, the top and middle layers of the conical shell have higher degree of recrystallization than the bottom layer. Along the thickness direction, the recrystallization degree first decreases and then increases from inside to outside. The interiors of the top and bottom layers are almost completely dynamic recrystallization, while others are mixed microstructure composed of coarse and fine grains. The top and bottom layers of the conical shell show obvious anisotropy in mechanical properties, while the middle layer is nearly isotropic, which is closely related to the difference in deformation mechanism caused by different crystal orientations of the samples. After aging treatment, the strength of the alloy is increased significantly, and the mechanical anisotropy is weakened, but the tensile fracture mode at room temperature changes from the mixed fracture mode of ductile fracture and brittle fracture to a single brittle fracture.
Key words: magnesium alloy; die forging; microstructure; mechanical properties; aging treatment
