(1. 黑龍江工程學(xué)院 機(jī)電工程學(xué)院，哈爾濱 150050；
2. 哈爾濱理工大學(xué) 材料科學(xué)與工程學(xué)院，哈爾濱 150040)
摘 要: 研究固相再生Mg-2.4Nd-0.4Zn-0.4Zr鎂合金等溫時(shí)效過(guò)程的析出強(qiáng)化行為。利用TEM、SEM對(duì)時(shí)效析出相的形態(tài)和斷裂行為進(jìn)行分析。結(jié)果表明:200 ℃、16 h 時(shí)效時(shí)合金力學(xué)性能達(dá)到峰值，抗拉強(qiáng)度為294.5 MPa，伸長(zhǎng)率為13.5%。此時(shí)，晶內(nèi)彌散析出桿狀β′亞穩(wěn)相和片狀β穩(wěn)定相，使合金獲得較高強(qiáng)度。在200 ℃、60 h 過(guò)時(shí)效作用下，β′亞穩(wěn)相原位長(zhǎng)大成β 穩(wěn)定相，合金的強(qiáng)度下降，塑性上升；欠時(shí)效時(shí)合金以穿晶剪切斷裂為主，峰時(shí)效時(shí)合金以穿晶韌窩和沿晶斷裂為主，過(guò)時(shí)效時(shí)粗大的第二相對(duì)斷裂過(guò)程有著較大的影響。
關(guān)鍵字: Mg-Nd-Zn-Zr鎂合金；時(shí)效強(qiáng)化；組織；力學(xué)性能；斷裂行為
（1. School of Mechanical and Electrical Engineering, Heilongjiang Institute of Technology, Harbin 150050, China;
2. School of Materials Science and Engineering, Harbin University of Science and Technology, Harbin 150040, China）
Abstract:The precipitation strengthening behavior of Mg-2.4Nd-0.4Zn-0.4Zr magnesium alloy prepared by solid recycling process during aging was investigated. The microstructure of the precipitates and fracture behavior were examined by TEM and SEM. The results show that the peak ultimate tensile strength, elongation of the alloy is 294.5 MPa and 13.5%, respectively, when aged at 200 ℃ for 16 h. The alloy exhibits good strength due to precipitation of the rod-like β′ metastable phase and the flaky β stable phase. The β′ phase transforms into the β stable phase in-situ when aged at 200 ℃ for 60 h. This induces decline of the strength and increasing of the plasticity. Fracture mode is mainly transgranular tearing fracture at the early stage of aging. Fracture mode is a mix mechanism with transgranular dimple fracture and intergranular fracture in the peak-ageing. Bigger second phases have largely effected on fracture in the further-ageing.
Key words: Mg-Nd-Zn-Zr magnesium alloy; aging strengthening; microstructure; mechanical property; fracture behavior
