工艺参数对梯度多孔Mg-Mn合金孔隙度和压缩强度的影响

以Mg、Mn、造孔剂碳酸氢铵为主要原料,采用粉末冶金技术制备梯度多孔Mg-Mn合金,研究了造孔剂分布、压制压力、烧结温度和Mn含量对梯度多孔Mg-Mn合金孔隙度和压缩强度的影响。结果表明,随着中间层造孔剂含量的降低和烧结温度的升高,梯度多孔Mg-Mn合金的孔隙度降低,压缩强度增加;随着压制压力的增加,烧结产物的孔隙度降低,压缩强度增加;随着Mn含量的增加,梯度多孔Mg-Mn合金的孔隙度先降低而后略有增加,压缩强度先增加而后降低。当Mn含量为2 wt%时,梯度多孔Mg-Mn合金孔壁烧结致密化程度最高,晶粒细化,烧结产物由单相α-Mg固溶体组成,压缩强度为34.1MPa。

固溶处理人工时效对不同锰含量的医用Mg-Mn合金性能的影响

制备Mg-1.0Mn、Mg-2.0Mn和Mg-3.0Mn三种不同锰含量的医用镁合金材料,对这三种镁合金进行固溶处理人工时效,分析该热处理前后三种镁合金的力学性能和腐蚀行为。结果表明,镁合金的硬度随锰含量的增加而增加;通过420℃8 h固溶处理和220℃48 h人工时效处理,三种镁合金都表现出较好的力学性能;合适的固溶处理人工时效工艺可以提高Mg-Mn合金的腐蚀电位,降低其在Hank's溶液中的腐蚀速率。

用于汽车制造业的Al-Cu-Mg-Mn合金

本发明推荐一种Al-Cu-Mg-Mn(3.8%～4.9%Cu，1.2%～1.8%Mg，0.3～0.9%Mn，≤0.35%Si，≤0.3%Fe，≤0.15%Ti)合金。该合金与现在广泛用于汽车制造业的2024合金相比，其断裂韧性高5%以上，疲劳裂纹增长速度慢，耐蚀性高，成形时的工艺能力高。Al-Cu-Mg-Mn合金半成品的生产方法包括：铸锭均匀化处理、热轧至2.54～6.35mm厚度、退火(383～468℃，1～12h)、冷轧(压下量≥40%）、热处理(493～499℃)及水淬。本专利还列出了添加元素的极限计算值及推荐的工艺过程。

机械合金化Mg-Mn合金的电化学腐蚀行为研究

采用高能球磨和热压烧结法制备Mn质量分数分别为1%、2%和3%的Mg-1Mn、Mg-2Mn和Mg-3Mn合金,研究其在SBF溶液中的腐蚀行为.将Mg-Mn合金在SBF溶液中动电位极化后,Mg-2Mn合金的自腐蚀电位约为-0.4V,Mg-1Mn合金的自腐蚀电位约为-1.4 V,Mg-3Mn合金的自腐蚀电位约为-1.62 V.在SBF中浸泡腐蚀后,三种合金的质量损失速度依次为:Mg-3Mn快于Mg-1Mn,最慢为Mg-2Mn.在Mg-1Mn、Mg-2Mn和Mg-3Mn合金中,Mg-2Mn合金在SBF溶液中的耐蚀性最好.

高电位镁合金(Mg-Mn)阳极熔体净化技术的研究

通过高电位镁阳极的熔铸及成型工艺中的净化技术研究,对试验样品进行了化学成分和电化学性能测试。结果表明:通过熔剂配方、熔炼操作、浇铸成型等技术的改进,保证了阳极的品质尤其是化学成分和电化学性能等符合要求,且保持相对稳定。

Er在Al-Mg-Mn-Zr-Er合金中的存在形式与析出特征

利用扫描电镜、透射电镜等分析测试手段,研究了Er在Al-4.7Mg-0.7Mn-0.1Zr-0.3Er合金铸态、均匀化态以及冷轧板中的存在形式及析出特征。结果表明,Er在非平衡凝固条件下部分固溶到基体α-Al中,大部分形成初生Al3Er相断续或连续分布在晶界上,Er容易与Mn、Fe元素发生偏聚,但是很难形成Er-Mn金属间化合物;固溶的Er在均匀化退火过程中以次生Al3Er相形式析出;而沿晶界分布的Al3Er相在随后的热处理过程中并不发生分解回溶,它们在热轧、冷轧过程中破碎;冷轧板中的次生Al3Er相与基体保持良好的共格、半共格关系,可以成为合金中有效的强化相。

Nd对Mg-2%Mn合金显微组织和力学性能的影响

通过光学显微镜、力学万能试验机和显微硬度仪等仪器分析了Mg-2%Mn-x%Nd合金的显微组织、力学性能和硬度。结果表明:Nd加入到Mg-2%Mn合金中,以Mg12Nd高温稳定相形式存在;Nd的加入细化了合金的晶粒,提高了合金的室温力学性能。

Comparison of FSW and TIG welded joints in Al-Mg-Mn-Sc-Zr alloy plates

In order to study the welding process,microstructure and properties of Al-Mg-Mn-Sc-Zr alloy,comparative methods of friction stir welding（FSW） and tungsten inert gas（TIG） were applied to the two conditions of this alloy,namely hot rolled plate and cold rolled-annealed plate.The relationships between microstructures and properties of the welded joints were investigated by means of optical microscopy and transmission electron microscopy.Compared with the base metal,the strength of FSW and TIG welded joints decreased,and the FSW welding coefficients were higher than the TIG welding coefficients.The loss of substructure strengthening and a very little loss of precipitation strengthening of Al3（Sc,Zr） cause the decreased strength of FSW welded joint.But for the TIG welded joint,the disappearance of both the strain hardening and most precipitation strengthening effect of Al3（Sc,Zr） particles contributed to its softening.At the same time,the grains in weld nugget zone of FSW welded joints were finer than those in the molten zone of TIG welded joints.

Crack elimination and strength enhancement mechanisms of selective laser melted Si-modified Al−Mn−Mg−Er−Zr alloy

In order to increase the processability and process window of the selective laser melting(SLM)-fabricated Al−Mn−Mg−Er−Zr alloy,a novel Si-modified Al−Mn−Mg−Er−Zr alloy was designed.The effect of Si alloying on the surface quality,processability,microstructure,and mechanical properties of the SLM-fabricated alloy was studied.The results showed that introducing Si into the Al−Mn−Mg−Er−Zr alloy prevented balling and keyhole formation,refined the grain size,and reduced the solidification temperature,which eliminated cracks and increased the processability and process window of the alloy.The maximum relative density of the SLM-fabricated Si/Al−Mn−Mg−Er−Zr alloy reached 99.6%.The yield strength and ultimate tensile strength of the alloy were(371±7)MPa and(518±6)MPa,respectively.These values were higher than those of the SLM-fabricated Al−Mn−Mg−Er−Zr and other Sc-free Al−Mg-based alloys.

中间合金配比对汽车用镁合金铸态组织与性能的影响

采用不同配比的Mg-Mn中间合金,制备了铸态Mg-3Al-1Zn合金,并通过显微组织和XRD分析,以及力学性能和耐腐蚀性能的测试发现:Mg-Mn中间合金配比,对铸态Mg-3Al-1Zn合金的显微组织、物相组成、力学性能和耐腐蚀性能产生明显影响,优选为Mg-5Mn;采用Mg-5Mn的抗拉强度较Mg-1Mn提高19.7%,较Mg-9Mn提高10.1%;采用Mg-5Mn的腐蚀电位较Mg-1Mn正移227 mV,较Mg-9Mn正移102 mV。

Effect of homogenization treatment on microstructure and properties of Al-Mg-Mn-Sc-Zr alloy

The effect of homogenization on the hardness,tensile properties,electrical conductivity and microstructure of as-cast Al-6Mg-0.4Mn-0.25Sc-0.12Zr alloy was studied.The results show that during homogenization as-cast studied alloy has obviously hardening effect that is similar to aging hardening behavior in traditional Al alloys.The precipitates are mainly Al3(Sc,Zr)and Al6Mn.When homogenization temperature increases the hardness peak value is declined and the time corresponding to hardness peak value is shortened.The electrical conductivity of the alloy monotonously increases with increasing homogenization temperature and time.The decomposition of the supersaturated solid solution containing Sc and Zr which is formed during direct chilling casting and the precipitation of Al3(Sc,Zr)cause hardness increasing.The depletion of the matrix solid solubility decreases the ability of electron scattering in the alloy,resulting in the electrical conductivity increased.Tensile property result at hot rolling state shows that the optimal homogenization treatment processing is holding at 300-350 ℃ for 6-8 h.

Effect of Y addition on microstructure and mechanical properties of Mg-Zn-Mn alloy

The effects of Y on the microstructure and mechanical properties of Mg-6Zn-lMn alloy were investigated. The results show that the addition of Y has significant effect on the phase composition, microstructure and mechanical properties of Mg-6Zn-lMn alloy. Varied phases compositions, including Mg7Zn3, I-phase （Mg3YZn6）, W-phase （Mg3Y2Zn3） and X-phase （MgI2YZn）, are obtained by adjusting the Zn to Y mass ratio. Mn element exists as the fine Mn particles, which are well distributed in the alloy. Thermal analysis and microstructure observation reveal that the phase stability follows the trend of X〉W〉/〉MgTZn3. In addition, Y can improve the mechanical properties of Mg-Zn-Mn alloy significantly, and the alloy with Y content of 6.09% has the best mechanical properties. The high strength is mainly due to the strengthening by the grain size refinement, dispersion strengthening by fine Mn particles, and introduction of the Mg-Zn-Y ternary phases.

Microstructure evolution and mechanical properties of Mg-x%Zn-1%Mn(x=4,5,6,7,8,9) wrought magnesium alloys

The roles of Zn content and thermo-mechanical treatment in affecting microstructures and mechanical properties of Mg-x%Zn-1%Mn（mass fraction,x=4,5,6,7,8,9） wrought Mg alloys were investigated.The microstructure was extremely refined by dynamic recrystallization（DRC） during extrusion.With increasing Zn content,the DRC grains tended to grow up,at the same time,more second phase streamlines would be present,which restricted the further growing.During solution treatment,the DRC grains would rapidly grow up;however,higher Zn content could hinder the grain boundary expanding,which results in finer ultimate grains.MgZn2 dispersoid particles which are coherent with the matrix would precipitate from the supersaturated solid solution during the one-step aging process,and nano-sized GP zones formed during the pre-aging stage of the two-step aging provide a huge amount of effective nuclei for the MgZn2 phases formed in the second stage,which makes the MgZn2 particles much finer and more dispersed.The mechanical properties of as-extruded samples were not so sensitive to the variation of Zn content,the tensile strength fluctuates between 300 and 320 MPa,and the elongation maintains a high value between 11% and 14%.The strength of aged samples rises as a parabolic curve with increasing Zn content,specifically,the tensile strength of one-step aged samples rises from 278 to 374 MPa,and that of two-step aged ones rises from 284 to 378 MPa,yet the elongation of all aged samples is below 8%.When Zn content exceeds its solid solution limit in Mg-Zn system（6.2%,mass fraction）,the strength rises slowly but the elongation deteriorates sharply,so a Mg-Zn-Mn alloy with 6% Zn possesses the best mechanical properties,that is,the tensile strengths after one-and two-step aging are 352 and 366 MPa,respectively,and the corresponding elongations are 7.98% and 5.2%,respectively.

Effects of heat treatment on microstructure and mechanical properties of Mg-3Sn-1Mn magnesium alloy

The effects of heat treatment on the microstructure and mechanical properties of Mg-3Sn-1Mn alloy were preliminarily investigated by using optical and electron microscopy,X-ray diffraction（XRD） analysis,and tensile and creep test.The results indicate that the heat treatment has an obvious effect on the microstructure and mechanical properties of the Mg-3Sn-1Mn alloy.After the solid solution treatment at 420 ℃,a majority of the Mg2Sn phases in the alloy are dissolved into the matrix.However,after the further aging treatment at 250 ℃,lots of fine Mg2Sn phases in the aged alloy are precipitated at the grain boundaries and within the grains.As a result,the tensile and creep properties of the aged alloy are significantly improved.The mechanism for the higher tensile and creep properties of the aged alloy is related to the dispersive distribution of the Mg2Sn phase in the--Mg matrix.

Microstructures and mechanical properties of extruded and aged Mg-Zn-Mn-Sn-Y alloys

The microstructures and mechanical properties of Mg-6Zn-1Mn-4Sn and Mg-6Zn-1Mn-4Sn-0.5Y alloys under extrusion and T6 aging conditions were investigated by optical microscopy（OM）, X-ray diffraction（XRD）, scanning electron microscopy（SEM） and tensile test. The results show that Y element refines the grains and improves the comprehensive mechanical properties of ZMT614-0.5Y both in as-extruded and T6 states. The phase compositions of Mg-6Zn-1Mn-4Sn-0.5Y are α-Mg, Mg Zn2, Mn, Mg2 Sn and Mg Sn Y phases. After T6 treatment, the ultimate tensile strength（UTS） and yield strength（YS） increase while the elongation decreases severely. For both of these alloys, the theoretical results combined with the experimental values demonstrate that the grain boundary strengthening and solid solution strengthening play an important role in enhancing the YS in the as-extruded state, while the precipitation strengthening is the key factor for the enhancement of YS in the T6 state.

Effects of minor Ca on as-cast microstructures and mechanical properties of Mg-3Ce-1.2Mn-0.9Sc and Mg-4Y-1.2Mn-0.9Sc alloys

The effects of the addition of 0.6%Ca（mass fraction） on the as-cast microstructure and mechanical properties of the Mg-3Ce-1.2Mn-0.9Sc and Mg-4Y-1.2Mn-0.9Sc magnesium alloys were investigated and compared by optical microscopy and scanning electron microscopy,differential scanning calorimetry analysis,and tensile and creep tests.The results indicate that the addition of 0.6%Ca to the Mg-3Ce-1.2Mn-0.9Sc and Mg-4Y-1.2Mn-0.9Sc alloys can refine the grains of the two alloys.At the same time,the addition of 0.6%Ca to the Mg-3Ce-1.2Mn-0.9Sc and Mg-4Y-1.2Mn-0.9Sc alloys can effectively improve the tensile properties of the two alloys.In addition,the addition of 0.6%Ca can also improve the creep properties of the Mg-3Ce-1.2Mn-0.9Sc alloy but is not beneficial to the creep properties of the Mg-4Y-1.2Mn-0.9Sc alloy.The different effects of minor Ca on the creep properties of the Mg-3Ce-1.2Mn-0.9Sc and Mg-4Y-1.2Mn-0.9Sc alloys are possibly related to the difference in the solid solubilities of Ce and Y in Mg.

Fabrication of lotus-type porous Mg−Mn alloys by metal/gas eutectic unidirectional solidification

Lotus-type porous Mg–xMn(x=0,1,2 and 3 wt.%)alloys were fabricated by metal/gas eutectic unidirectional solidification(the Gasar process).The effects of Mn addition and the fabrication process on the porosity,pore diameter and microstructure of the porous Mg-Mn alloy were investigated.Mn addition improved the Mn precipitates and increased the porosity and pore diameter.With increasing hydrogen pressure from 0.1 to 0.6 MPa,the overall porosity of the Mg-2wt.%Mn ingot decreased from 55.3%to 38.4%,and the average pore diameter also decreased from 2465 to 312μm.Based on a theoretical model of the change in the porosity with the hydrogen pressure,the calculated results were in good agreement with the experimental results.It is shown that this technique is a promising method to fabricate Gasar Mg–Mn alloys with uniform and controllable pore structure.

Enhanced mechanical properties and formability of hot-rolled Mg-Zn-Mn alloy by Ca and Sm alloying

In order to broaden the application of wrought Mg alloy sheets in the automotive industry,the influence of Ca and Sm alloying on the texture evolution,mechanical properties,and formability of a hot-rolled Mg-2Zn-0.2Mn alloy was investigated by OM,XRD,SEM,EBSD,tensile tests,and Erichsen test.The results showed that the average grain size and basal texture intensity of Mg-2Zn-0.2Mn alloys were remarkably decreased after Ca and Sm additions.0.64 wt.%Ca or 0.48 wt.%Sm addition significantly increased the tensile strength,ductility and formability.Moreover,the synergetic addition of Sm and Ca improved the ductility and formability of Mg-2Zn-0.2Mn alloy,which was due to the change of Ca distribution and further reduction of the size of Ca-containing particles by Sm addition.The results provided a possibility of replacing RE elements with Ca and Sm in Mg alloys which bring about outstanding mechanical properties and formability.

Effect of Al addition on microstructure and mechanical properties of Mg−Zn−Sn−Mn alloy

The microstructure and properties of the as-cast,as-homogenized and as-extruded Mg−6Zn−4Sn−1Mn(ZTM641)alloy with various Al contents(0,0.5,1,2,3 and 4 wt.%)were investigated by OM,XRD,DSC,SEM,TEM and uniaxial tensile tests.The results show that when the Al content is not higher than 0.5%,the alloys are mainly composed of α-Mg,Mg_(2)Sn,Al_(8)Mn_(5)and Mg_(7)Zn_(3)phases.When the Al content is higher than 0.5%,the alloys mainly consist ofα-Mg,Mg_(2)Sn,MgZn,Mg_(32)(Al,Zn)_(49),Al_(2)Mg_(5)Zn_(2),Al_(11)Mn_(4)and Al_(8)Mn_(5)phases.A small amount of Al(≤1%)can increase the proportion of fine dynamic recrystallized(DRXed)grains during hot-extrusion process.The roomtemperature tensile test results show that the ZTM641−1Al alloy has the best comprehensive mechanical properties,in which the ultimate tensile strength is 332 MPa,yield strength is 221 MPa and the elongation is 15%.Elevatedtemperature tensile test results at 150 and 200℃ show that ZTM641−2Al alloy has the best comprehensive mechanical properties.

Effect of Si content on laser welding performance of Al-Mn-Mg alloy

The correlation between Si content （0.1%-0.5%, mass fraction） and pulse laser welding performance of AI-Mn-Mg aluminum alloy sheets was studied. The sheets were fabricated in the laboratory, with gauge of 0.45 mm, H16 temper by pulse laser welding. It was found that no cracking existed in the welding pool as Si content was below 0.34%. However, when the Si content increased to 0.47%, cracking formed in the welding pool. Microstructure observations indicated that residual eutectic phases distributed at the grain boundaries were discontinuous and appeared to be small particles in lower Si content alloys; the residual eutectic phases distributed at the grain boundaries were partially continuous and appeared to be films in higher Si content alloys. These phenomena could explain why Si content adversely affected the laser welding performance.