(1. 有研科技集團(tuán)有限公司國(guó)家有色金屬及電子材料分析測(cè)試中心，北京 100088；
2. 國(guó)合通用測(cè)試評(píng)價(jià)認(rèn)證股份公司，北京 101407；
3. 北京有色金屬研究總院，北京 100088；
4. 國(guó)標(biāo)(北京)檢驗(yàn)認(rèn)證有限公司，北京 101407；
5. 有研工程技術(shù)研究院有限公司 有色金屬材料制備加工國(guó)家重點(diǎn)實(shí)驗(yàn)室，北京 101407)
摘 要: 采用掃描電子顯微鏡、電子背散射衍射、透射電子顯微鏡、高角度環(huán)形暗場(chǎng)-掃描透射，分析了Mg-7Gd-5Y-1Nd-xZn-0.5Zr(x=0, 1, 2, 質(zhì)量分?jǐn)?shù)，%)擠壓態(tài)合金微觀(guān)組織結(jié)構(gòu)和力學(xué)性能，旨在探索Zn對(duì)于合金性能影響的微觀(guān)機(jī)制。結(jié)果表明：在Mg-7Gd-5Y-1Nd-0.5Zr合金中添加Zn元素，不僅形成LPSO結(jié)構(gòu)，也促進(jìn)了Mg5(RE, Zn)顆粒的析出，并與Zr形成Zn-Zr相。LPSO結(jié)構(gòu)不僅能阻礙晶粒長(zhǎng)大，細(xì)化晶粒；也能夠阻礙動(dòng)態(tài)再結(jié)晶，從而形成動(dòng)態(tài)再結(jié)晶晶粒和變形晶粒共存的雙模結(jié)構(gòu)，動(dòng)態(tài)再結(jié)晶晶粒為 //ED織構(gòu)，變形晶粒為 //ED織構(gòu)。微米級(jí)大尺寸Mg5(RE, Zn)顆粒會(huì)導(dǎo)致應(yīng)力集中，引起裂紋的萌生，降低合金的塑性；均勻分布的亞微米級(jí)Mg5(RE, Zn)顆粒起第二相強(qiáng)化作用，并能釘扎晶界，阻礙晶粒長(zhǎng)大。對(duì)比3種擠壓態(tài)合金，Mg-7Gd-5Y-1Nd-2Zn-0.5Zr合金獲得了最優(yōu)的力學(xué)性能，其抗拉強(qiáng)度、屈服強(qiáng)度和伸長(zhǎng)率分別為365 MPa、276 MPa和17.5%。
關(guān)鍵字: 鎂合金；擠壓；長(zhǎng)程堆垛有序(LPSO)結(jié)構(gòu)；HAADF-STEM；力學(xué)性能
（1. National Center of Analysis and Testing for Nonferrous Metals and Electronic Materials, GRINM Group Co., Ltd., Beijing 100088, China;
2. China United Test and Certification Co., Ltd., Beijing 101407, China;
3. Beijing General Research Institute for Nonferrous Metals, Beijing 100088, China;
4. Guobiao (Beijing) Testing and Certification Co., Ltd., Beijing 101407, China;
5. State Key Laboratory of Nonferrous Metals and Processes, GRIMAT Engineering Institute Co., Ltd., Beijing 101407）
Abstract:The microstructure and mechanical properties of extruded Mg-7Gd-5Y-1Nd-xZn-0.5Zr (x=0, 1, 2, mass fraction, %) alloys were investigated by scanning electron microscope(SEM), transmission electron backscattered diffraction(EBSD) and high-angle annular dark-field scanning transmission electron microscopy(HAADF-STEM). The addition of Zn element can form long period stacking ordered (LPSO) structures, promote the precipitation of Mg5(RE, Zn) phases and form Zn-Zr compounds with Zr element. LPSO structures can not only restrict grain growth, refines grain, but also prevent dynamic recrystallization, resulting in dynamic recrystallization grains and deformable grains coexisted, the DRX grains with a //ED texture, and the deformed grains with //ED texture. The large size micron-scale Mg5(RE, Zn) particles can reduce the toughness and plasticity of the alloy, the uniformly distributed submicron-scale Mg5(RE, Zn) particles play the role of second phase strengthening and can nail grain boundaries, and hinder grain growth. For three extruded alloys, the Mg-7Gd-5Y-1Nd-2Zn-0.5Zr alloy obtains the optimal mechanical properties, the tensile strength, yield strength and elongation are 365 MPa, 276 MPa and 17.5%, respectively.
Key words: magnesium alloys; extrusion; long-period stacking ordered (LPSO) structures; HAADF-STEM; mechanical properties
