多方向锻造对ZK60镁合金组织和力学性能的影响

对ZK60镁合金在350℃进行了多方向锻造,并通过固溶处理提高铸态ZK60的塑性。结果表明,通过固溶处理能够有效地消除第二相组织以获得均匀的组织结构。通过一次锻造后,ZK60镁合金发生再结晶,多次锻造后获得细小均匀的微观组织,晶粒尺寸能够达到1.5μm。多方向锻造后ZK60镁合金的力学性能得到提高,锻造6次后材料强度提升约81.3%,伸长率提高约180%。     

往复挤压温度对ZK60镁合金组织与性能的影响

采用往复挤压工艺，对ZK60镁合金进行不同温度往复挤压，分析往复挤压温度对组织和性能的影响。结果表明：在315℃、335℃和355℃往复挤压ZK60镁合金，其中335℃时晶粒细化效果最好，材料的综合力学性能最佳。往复挤压工艺可以显著降低ZK60镁合金的热膨胀系数，提高ZK60镁合金的热稳定性。     

热变形对ZK60镁合金组织及性能的影响

对ZK60镁合金进行了平面应变等温压缩试验,并对不同变形条件下压缩试样的微观组织、拉伸性能进行分析.结果表明,ZK60合金热变形后力学性能得到提高,尤其是塑性得到较大改善,伸长率最高达到38％,断口形貌由河流状变为韧窝状,这主要是由于变形过程中产生动态再结晶,使晶粒明显细化;均匀态组织中个别未溶的共晶组织呈点状断续分布于晶界上,这些点状裂纹在变形过程中不易扩展还可能愈合;在300～380℃对均匀态ZK60合金进行平面压缩后,可获得较优的综合力学性能.     

时效温度对ZK60镁合金组织和性能的影响

对ZK60镁合金在100～220℃进行时效处理,通过金相组织分析、断口扫描分析及力学性能测试,研究了时效温度对ZK60镁合金的显微组织与力学性能的影响.结果表明:时效处理能明显改善ZK60镁合金的组织和力学性能.其力学性能随时效温度升高呈规律性变化,网络结构是力学性能变化的主要原因.得出ZK60镁合金力学性能的优化时效温度为190℃.     

稀土元素对ZK60镁合金组织和性能影响的研究现状

简述了稀土元素在镁合金中的作用,重点介绍了Y、Ce、Er、Nd、Dy、Gd、Yb等稀土元素对ZK60镁合金的晶粒尺寸、第二相化合物、室温力学性能以及高温性能的影响,指出了在ZK60镁合金中添加稀土元素的研究存在的问题与不足,并对其发展方向进行了展望.     

经电脉冲处理的轧制AZ31镁合金组织与性能演变

利用超景深显微镜、扫描电镜(SEM)、电子背散射衍射(EBSD)研究了高能量脉冲电流对10%、15%、20%不同轧制变形量AZ31镁合金组织演化与力学性能的影响。当变形量为20%的轧制板材经电流密度为4.16×10~9 A/m~2、脉宽为30μs、频率为100 Hz的脉冲电流处理10 min后,平均晶粒尺寸由150μm细化至20μm,抗拉强度提升至265 MPa,伸长率可达19.7%。同时,分析了此实验参数下电脉冲处理过程中热效应与非热效应对再结晶的影响,发现热效应在再结晶过程中占主导作用,并揭示了非热效应的作用机理。     

ZK60镁合金板材成形性能试验

对ZK60镁合金板材在室温和高温条件下进行杯突试验。试验结果表明,室温下ZK60镁合金板材杯突值IE=4.5mm,在370℃条件下材料的杯突值IE=16.5mm,胀形高度增加了266.7%;ZK60镁合金板材高温胀形的破裂,是由冲头附近板材沿切向方向的裂纹扩展和沿厚度方向缩颈所产生的断裂造成。     

热处理工艺对挤压变形ZK60镁合金组织与力学性能的影响

采用硬度检测、拉伸实验、金相分析、TEM分析等方法测试和分析了ZK60合金在铸态、挤压态、固溶态及T5和T6时效态下的硬度、强度和显微组织等。结果表明：ZK60镁合金在塑性变形和不同热处理状态下硬度和强度等力学性能变化明显。经过挤压和T5热处理后，ZK60合金的硬度和强度都大幅度提高。ZK60合金挤压后进行T5处理，其强度要比T6处理的强度明显要高，这与T5状态下合金中析出强化相分布更加密集和细小有关，T6热处理时，由于第二相尺寸以及相互间距都较大，因此强化效果反而不如T5状态。     

铈含量对ZK60镁合金组织和性能的影响

以ZK60合金成分为基础，添加质量百分比分别为0，0．5％，1．0％，1．5％和2％的铈（Ce），研究不同Ce含量和加工处理状态对合金力学性能和显微组织的影响。结果表明：未添加Ce的ZK60合金晶粒粗大且晶界偏析严重，而添加Ce后的合金晶粒明显细化，晶界得到净化。经过热挤压后，合金都发生了明显的动态再结晶。同时，合金的强度随Ce含量的增加而上升，在150℃时效0～24h（T5处理）后，抗拉强度和伸长率均得到了不同程度的提高。其中4合金具有最优的综合性能：挤压态σb。=318．6MPa，δ=14．4％；24h时效后σb=338．6MPa，δ=15．6％。     

喷丸强化对ZK60镁合金高周疲劳性能的影响

研究高强度变形镁合金ZK60经喷丸处理后的表面变形层微观组织结构的变化及其对高周疲劳性能的影响.结果表明:ZK60镁合金的最佳喷丸强度(N试片)为0.05 mm,经喷丸强化后,ZK60镁合金表面变形层的微观组织和织构发生变化,疲劳强度由140MPa提高到180MPa,提高约29%,疲劳寿命得到显著提高;ZK60镁合金也表现出明显的过喷效应.     

Influence of aging on microstructure and properties of ZK60 magnesium alloy

The different aging process was investigated for ZK60 magnesium alloy to get the ideal synthetic properties. The results show that the values of strength, hardness and plasticity of ZK60 magnesium alloy increase at first and then decrease with increasing aging temperature, the suitable aging temperature of ZK60 alloy is from 160 to 180 ℃, At the meantime, the microstructures of appear mesh texture under high ageing temperature, this is the main reason why the mechanical properties decrease.     

Influence of impurities on microstructure and mechanical properties of ZK60 magnesium alloy

The influence of impurity content on the microstructure and mechanical properties of ZK60 magnesium alloys was investigated by optical microscopy, scanning electron microscopy and tensile test. ZK60 alloys were prepared by changing holding time of alloy melt during semi-continuous casting in order to control the content of impurity elements. The alloy with lower purity content is found to have less second precipitates and larger grain size in the as-cast state. However, in the as-extruded state, reducing impurities brings about a decrease in grain size and an increase in yield strength from 244 MPa to 268 MPa, while the elongations in the as-extruded alloys with different contents of impurities are almost the same. After T5 treatment, impurity content is found to have more obvious effect on the yield strength of ZK60 alloy. The yield strength of ZK60-45 alloys with low impurity content is increased up to 295 MPa after T5 treatment.     

轧制路径对ZK60镁合金板材组织和性能的影响

在250 ℃对轧制-热处理态ZK60镁合金板材进行9道次不同路径的轧制试验。采用光学显微镜、电子万能试验机、SEM、XRD等研究了轧制试验后ZK60镁合金的显微组织、室温拉伸性能、断口形貌及晶粒择优取向。结果表明:轧制路径对ZK60镁合金板材的晶粒尺寸变化无明显影响,但压下量对镁合金组织内的孪晶变化有很大影响;轧制路径的变化对ZK60镁合金板材的各向异性和力学性能有较大影响,在交叉+45°的路径下轧制后ZK60镁合金板材,各向异性较弱,具有良好的综合力学性能和轧制成形能力,其屈服强度、抗拉强度和伸长率分别达到244.31 MPa、371.14 MPa和25.46%;交叉+45°路径轧制对ZK60镁合金的晶粒择优取向有明显影响,能够改善镁合金板材的晶粒择优取向和各向异性,提高ZK60镁合金的力学性能。     

Influence of impurities on damping properties of ZK60 magnesium alloy

The influence of impurities on damping capacities of ZK60 magnesium alloys in the as-cast, as-extruded and T4-treated states was investigated by dynamically mechanical analyzer at room temperature. Granato and Lucke dislocation pinning model was employed to explain damping properties of the alloys. It is found that reducing impurity content can decrease the amount of second-phase particles, increase grain size and improve damping capacity of the as-cast alloy slightly. The as-extruded alloy with lower impurity content is found to possess obviously higher damping capacity in the relatively high strain region than that with higher impurity concentration, which appears to originate mainly from different dislocation characteristics. The variation tendency of damping property with change of impurity content after solution-treatment is also similar to that in the as-extruded and as-cast states. Meanwhile, the purification of the alloy results in an evident improvement in tensile yield strength in the as-extruded state.     

Effect of large deformation on microstructure of ZK60 alloy

Microstructure evolution of ZK60 magnesium alloy deformed at 023 hoy cyclic extrusion compression （CEC） large deformation method was investigated. ZK60 alloy was deformed in the range of accumulated true strain of 0.8-17. The microstructure of evolution was investigated by optical microscope （OM） and transmission electron microscopy （TEM）. The results show that microstructure is obviously refined, and homogenous equiaxed microstructure is achieved in the entire range of the examined deformations by subjected to CEC deformation. By increasing the accumulated strain to 17, the grain size decreases into sub-micron regime with about several hundred nanometers. The mechanism of grain refinement in ZK60 alloy by CEC can be attributed to continuous dynamic recovery and recrystallization.     

脉冲电流轧制对AZ31镁合金微观组织与力学性能的影响

对比研究脉冲电流轧制工艺与温轧工艺对AZ31镁合金板材的力学性能、织构、微观组织与沉淀相等方面的影响。结果表明：脉冲电流具有促进冷轧AZ31镁合金低温再结晶能力的作用。脉冲电流轧制后的镁合金板材组织由细小的等轴再结晶粒与析出相构成,没有发现孪晶组织,并且完全再结晶,原始晶粒均被细小的再结晶晶粒取代,再结晶晶粒内的位错密度低。而温轧镁合金组织则由稍拉长变形孪晶、粗大的再结晶晶粒和析出相构成,再结晶的晶粒内位错密度高。两种轧制方式下的镁合金析出相均为Mg17Al12。脉冲电流轧制后镁合金的织构具有典型基面织构的特征,而脉冲电流轧制镁合金的织构则出现横向偏转;脉冲电流轧制后镁合金的屈服强度与伸长率均比温轧镁合金的大,但抗拉强度正好相反。     

电脉冲对轧制AZ31镁合金组织与性能的影响

研究了电脉冲处理(EPT)对轧制变形AZ31镁合金组织演化与力学性能的影响。使用脉冲电源产生的高电流密度低占空比电脉冲促进了变形AZ31镁合金内部的再结晶进程。通过对不同参数脉冲处理的对比分析,研究了电脉冲的热效应与非热效应的作用,揭示了电脉冲促进再结晶的作用机理。结果表明:AZ31镁合金经过脉宽为20ms、电流密度3.508×109A/m~2、占空比为0.002的电脉冲处理5.5 min后,在电脉冲的非热作用下发生再结晶,平均晶粒尺寸由72mm减小至2mm,抗拉强度提升85%,达到295 MPa,延伸率达到20%。