热处理对挤压镁合金AZ91拉伸变形与断裂行为的影响

通过金相显微组织观察和断口SEM分析,研究了热处理对挤压AZ91镁合金拉伸变形与断裂行为的影响。结果表明:AZ91镁合金固溶态与挤压态相比抗拉强度变化不大,但伸长率有较大幅度的提高,晶粒尺寸有所增大;时效峰值态的抗拉强度与固溶态相比有一定的提高,但伸长率有较大幅度的降低,合金固溶时效处理后伴有强化相粒子析出。AZ91合金挤压态和固溶态的断面都有韧窝特征,为微孔形核的韧性断裂机制,而在时效峰值态的断面上则呈现出了韧性与脆性混合断裂的特征。     

热处理对挤压镁合金AZ91拉伸变形与断裂行为的影响

通过金相显微组织观察和断口SEM分析，研究了热处理对挤压AZ91镁合金拉伸变形与断裂行为的影响。结果表明：AZ91镁合金固溶态与挤压态相比抗拉强度变化不大，但伸长率有较大幅度的提高，品粒尺寸有所增大；时效峰值态的抗拉强度与固溶态相比有一定的提高，但伸长率有较大幅度的降低，合金固溶时效处理后伴有强化相粒子析出。AZ91合金挤压态和固溶态的断面都有韧窝特征，为微孔形核的韧性断裂机制，而在时效峰值态的断面上则呈现出了韧性与脆性混合断裂的特征。     

热处理对挤压镁合金ZK60拉伸变形与断裂行为的影响

通过不同态ZK60镁合金的金相显微组织观察、力学性能试验和断口SEM分析,研究了热处理对挤压ZK60镁合金拉伸变形与断裂行为的影响.结果表明,ZK60合金固溶态与挤压态相比抗拉强度和伸长率均有相当程度的降低,而时效硬度峰值时的抗拉强度与固溶态和挤压态相比有一定的提高,但伸长率却有较大幅度的降低.合金固溶处理后晶粒较挤压态显著粗化,且合金固溶时效处理后伴有强化相粒子析出.ZK60合金挤压态和固溶态的断面都有韧窝特征,为微孔形核的韧性断裂机制,而时效峰值态的断面上有解理河流和解理台阶,呈现出脆性解理断裂的特征.     

铸态晶粒尺寸对AZ91合金固溶时效行为的影响

研究铸态晶粒尺寸对AZ91合金固溶时效组织的影响,并对析出相与合金显微硬度之间的关系进行了分析.结果表明,合金铸态晶粒尺寸越小,其固溶效率越高,时效处理时β相的连续析出速度越快;在时效处理过程中,无论铸态晶粒尺寸或大或小,合金的显微硬度值都随着连续析出的β相数量的增加先升高后降低;并且铸态晶粒尺寸越小,其硬度峰值越高,达到峰值所用的时间越短.     

热处理对往复挤压态Mg-4Al-2Si合金组织和性能的影响

研究了往复挤压态Mg-4Al-2Si合金经固溶处理及固溶 时效处理后的组织与性能.结果表明,固溶处理后合金的硬度、抗拉强度与屈服强度均降低,伸长率出现最大值;经固溶 时效处理后合金的晶粒明显长大,硬度、抗拉强度及塑性降低,屈服强度降低显著.合金挤压态与往复挤压后固溶处理态的断裂形式为韧性断裂;挤压态合金经过固溶 时效处理后的断裂形式为脆性准解理断裂.     

热处理对ZK60轧制镁合金组织与力学性能的影响

通过力学性能测试及金相组织观察对ZK60镁合金轧件的热处理工艺进行了研究。结果表明,在固溶状态(T4),伸长率明显提高,但拉伸强度下降;与T4处理的合金比较,时效处理(T6)时的抗拉强度明显提高,但伸长率有较大幅度降低。轧制的ZK60镁合金T4处理后晶粒尺寸比母材明显增大。T6处理后合金伴有强化相粒子析出。     

新型Cu-Al-Fe-Ni变形铝青铜的固溶和时效强化

采用正交试验法,结合金相、X射线衍射、扫描电镜、能谱和力学性能等分析测试手段,对一种自主研发的Cu-Al-Fe-Ni变形铝青铜的固溶和时效强化工艺进行研究。结果表明:固溶时效工艺参数对合金抗拉强度、伸长率和硬度的作用主次顺序为时效温度、固溶温度、时效时间、固溶时间,其中温度对合金力学性的影响趋势单一,但时间的影响较复杂。经优化获得的最佳固溶时效工艺为:先在880℃下固溶3 h、水淬,再在480℃下时效1 h、空冷。合金的抗拉强度达810 MPa,伸长率达9%,硬度达255 HB,其综合力学性能比挤压态合金的有较大幅度的提高;软硬相的面积比及其显微硬度对合金的力学性能有较大的影响。     

坯料预处理对挤压AZ91D管件组织和力学性能的影响

研究了挤压比为6时镁合金AZ91D坯料前期分别经过预挤，固溶时效，预挤＋固溶时效，预挤＋固溶时效＋固溶之后对挤压管件组织和力学性能的影响。结果表明：预挤使AZ91D坯料得到细化的等轴晶粒，使挤压出的管件的屈服强度提高15．72％，伸长率提高170％；坯料经固溶时效处理后，β—Mg17Al12：从α—Mg固溶体中成断续状析出，挤压后管件的抗拉强度略有降低；坯料经预挤＋固溶时效＋固溶之后挤压管件，晶粒明显细化，且经二次固溶，析出相均匀弥散分布于基体中，固溶强化作用较第一次固溶时明显，抗拉强度提高7．5％，坯料的二次固溶和预挤的综合作用使得挤压管件的伸长率提高345％。     

挤压和T5处理对铸态ZK60镁合金组织性能的影响

对铸态ZK60镁合金进行了挤压，对挤压后的试样进行了T5处理，分析了该材料三种状态时力学性能和微观组织变化。结果表明：铸态ZK60镁合金挤压后，晶粒明显细化，各项力学性能显著提高；T5处理后试样的抗拉强度和硬度比T5处理前的相应值均有所提高，屈服强度明显提高，伸长率稍有降低；ZK60镁合金在挤压时，其组织中已有细小第二相析出；经T5处理后，其晶粒尺寸变化不大，析出相较挤压态时有明显增多，但部分聚集长大。     

挤压铸造工艺对含Y2wt% AZ91D稀土镁合金组织与性能的影响

研究了挤压铸造工艺参数(挤压压力、浇注温度和保压时间)对含2wt%Y的AZ91D稀土合金组织与性能的影响。采用X射线衍射、金相分析、拉伸试验和SEM等方法分析了合金挤压态和固溶时效态的显微组织及其力学性能。结果表明:浇注温度对镁合金组织和性能影响最大,挤压压力其次,最后是保压时间。试验获得最佳工艺参数为:浇注温度720℃、挤压压力100 MPa、保压时间25 s。试样最大抗拉强度达到241.56 MPa、伸长率12.4%、布氏硬度80.06HB。固溶时效后铸件的力学性能明显提高,组织晶粒更细小且分布均匀。     

Mechanical properties and microstructures of a wrought AZ91 alloy

Effects of hot plastic deformation on microstructures and tensile properties of AZ91 alloy were investigated. Compared with as-T4 microstructures, the as-extruded samples of AZ91 alloy with fine grains exhibit better strength and ductility due to dynamic recrystallization. The succeeded rotation forging also provides freer grains while the strength increases, but the elongation decreases. Simultaneously, wrought AZ91 alloy shows more balance properties than as-T4 condition ones. An interesting elongation of 228.5% is attained in the as-extruded AZ91 alloy in spite of the coarse grains with the size of 85 μm. The two-step method enhances the superplastic property of AZ91 alloy. The microstructure is still keeping the same scale of grains after superplastic testing.     

Suppression of discontinuous precipitation in AZ91 by addition of Sn

The effect of Sn (5 wt%) addition on the aging behavior of the AZ91 alloy has been investigated in the present study. The addition of Sn effectively suppresses the discontinuous precipitation during aging treatment. The aging response of the Sn containing AZ91 alloy is far better than that of the AZ91 alloy due to much higher density of continuous precipitation in the matrix. The yield strength and total elongation to failure at the peak aged condition of the AZ91 and Sn containing AZ91 alloys are 119.4 and 161.9 MPa and 8.8 and 8.6%, respectively, indicating that 35.6% increase of yield strength can be obtained by the addition of Sn in the AZ91 alloy maintaining almost same level of ductility.     

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.     

在线固溶及离线热处理对压铸AZ91D镁合金组织及硬度的影响(英文)

研究在线固溶处理、离线固溶处理和时效处理对压铸AZ91D镁合金组织及硬度的影响。结果表明:在线淬火和离线时效处理可提高压铸AZ91D合金的布氏硬度,但是离线固溶处理使合金的硬度下降。通过X射线物相分析、光学显微组织分析、差热分析、扫描电镜及能谱分析,发现在线固溶和时效处理后合金的组织与压铸AZ91D的基本相同,仍由α-Mg及β-Al12Mg17组成。在压铸镁合金冷却过程中,在线固溶处理使温度急剧降低从而阻止了β-Al12Mg17相的继续析出,增强了Al元素固溶强化的效果。时效处理后,Al12Mg17从Mg的过饱和固溶体中析出并细化组织,改善了细晶强化的效果。离线的固溶处理使Al12Mg17分解,导致其固溶强化效果得到增强但是晶界强化相大幅度减少,从而使合金的硬度降低。     

时效处理对挤压成型2195铝锂合金组织和力学性能的影响

研究了热处理对挤压态2195铝锂合金组织和力学性能的影响。结果表明,固溶处理和人工时效处理对挤压合金的力学性能有显著的增强作用,这与析出相的类型、尺寸、数量密度和分布有关。2195铝锂合金在时效过程中的析出顺序为过饱和固溶体(SSSS)→GP区+δ′/β′(Al₃(Li,Zr))→δ′+θ′(Al₂Cu) +T₁ (Al₂CuLi)→θ′+T₁;其中T₁相在析出强化中起主导作用。2195铝锂合金经过525 ℃×60 min固溶后在170 ℃人工时效的峰时效时间是36 h,此时抗拉强度、屈服强度和伸长率分别为579 MPa、537 MPa和5.5%。     

Comparison of corrosion behaviors of AZ31, AZ91, AM60 and ZK60 magnesium alloys

The corrosion behaviours of four kinds of rolled magnesium alloys of AZ31, AZ91, AM60 and ZK60 were studied in 1 mol/L sodium chloride solution. The results of EIS and potentiodynamic polarization show that the corrosion resistance of the four materials is ranked as ZK60＞AM60＞AZ31＞AZ91. The corrosion processes of the four magnesium alloys were also analyzed by SEM and energy dispersive spectroscopy(EDS). The results show that the corrosion patterns of the four alloys are localized corrosion and the galvanic couples formed by the second phase particles and the matrix are the main source of the localized corrosion of magnesium alloys. The corrosion resistance of the different magnesium alloys has direct relationship with the concentration of alloying elements and microstructure of magnesium alloys. The ratio of the β phase in AZ91 is higher than that in AZ31 and the β phase can form micro-galvanic cell with the alloy matrix, as a result, the corrosion resistance of AZ31 will be higher than AZ91. The manganese element in AM60 magnesium alloy can form the second phase particle of AlMnFe, which can reduce the Fe content in magnesium alloy matrix, purifying the microstructure of alloy, as a result, the corrosion resistance of AM60 is improved. However, due to the more noble galvanic couples of AlMnFe and matrix, the microscopic corrosion morphology of AM60 is more localized. The zirconium element in ZK60 magnesium alloy can refine grain, form stable compounds with Fe and Si, and purify the composition of alloy, which results in the good corrosion resistance of ZK60 magnesium alloy.     

Analysis on flow stress of magnesium alloys during high temperature deformation

The flow stress of magnesium alloys during hot compression at different temperatures and strain rates was studied by experiments.Materials used were AZ91D alloys in as-cast,homogeneous treatment states,AZ31 and ZK60 alloys in as-cast state. The results show that the thermal simulation curves of different alloys differ from one another at the same deforming condition.The general curves of AZ31 and AZ91D alloys have the character of dynamic recrystallization.There are increase of true stress,drastic fallin...     

固溶时效处理对挤压态6082铝合金力学性能和组织的影响

采用拉伸试验机、光学显微镜和透射电镜等方法研究了固溶和时效处理工艺对挤压态6082铝合金力学性能和组织的影响。结果表明,经530 ℃固溶处理的试样强度高于550 ℃固溶处理的试样,经不同固溶温度处理后合金表现出不同的力学性能各向异性行为,而经时效处理后合金的屈服强度显著提升。550 ℃固溶处理的合金,晶粒明显长大。经时效处理后的试验合金中分布着大量的针状析出相,能有效阻碍位错的运动,提升材料的强度。经不同固溶+时效处理后的挤压态试验合金拉伸断口处均发现大量的韧窝,表现出韧性断裂的特征。