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.     

Microstructures and mechanical properties of the extruded Mg-4Y-2Gd-xZn-0.4Zr alloys

Microstructures and mechanical properties of the Mg-4Y-2Gd-0.4Zr alloy with Zn additions have been investigated. The investigation suggests that the mechanical properties of the alloys have been greatly improved after hot extrusion due to the refinement of microstructures, especially the elongations. The extruded Mg-4Y-2Gd-1.0Zn-0.4Zr alloy displays excellent tensile properties. The ultimate tensile strength and the yield tensile strength are 291 and 228 MPa, respectively, with an elongation of 28%. The additions of Zn have an obvious effect on refining microstructure of the extruded alloys, and the vicker hardness increases with increasing Zn additions. The age hardening responses of the extruded alloys have been investigated at 220 °C. These alloys display unobvious ageing hardness responses.     

Microhardness and Tensile Properties of a 6XXX Alloy Through Minor Additions of Zr

The 6XXX series alloy is known to show inferior age-hardening response during the paint-bake cycle due to natural aging prior to the paint-bake. Many researchers have adopted the pre-aging process to offset the detrimental effect of the natural aging process. The alloy used in this study contained excess Si, and it had been reported elsewhere that such alloys do not show positive response to the pre-aging process. The present work is aimed to study the microhardness and tensile strength of the Al-1.2Si-0.5Mg-0.25Fe wrought alloy through Zr additions between 0.02 and 0.30 wt.%. Alloys containing 0.15 wt.% Zr and above heat-treated for 30 min gave higher microhardness and ultimate tensile strength values compared to that of Al-1.2Si-0.5Mg-0.25Fe without Zr which was heat-treated for 11 h. It was found that mechanical properties improved when the Zr content in the alloys increased. The improvement of mechanical properties was mainly attributed to formation of Zr-bearing intermetallic compounds formed in the alloy.     

Effects of Minor Sr on As-Cast Microstructure and Mechanical Properties of ZA84 Magnesium Alloy

The effects of minor Sr additions on the as-cast microstructure and mechanical properties of the ZA84 magnesium alloy were investigated. The results indicate that adding 0.05-0.15 wt.% Sr to the ZA84 alloy does not cause an obvious change in the morphology and distribution of the Mg₃₂(Al,Zn)₄₉ phase. However, the grains of the Sr-containing ZA84 alloys are effectively refined. Among the Sr-containing ZA84 alloys, the grains of the alloy added 0.10 wt.% Sr are relatively finer than other alloys. Furthermore, adding 0.05-0.15 wt.% Sr to the ZA84 alloy improves the tensile properties at room temperature and 150 °C but decreases the creep properties. Among the Sr-containing ZA84 alloys, the alloy added 0.10 wt.% Sr obtains the optimum tensile properties at room temperature and 150 °C.     

Zn对Mg-10Gd-2Y-0.5Zr镁合金组织和性能的影响

通过在Mg-10Gd-2Y-0.5Zr合金中添加Zn,采用SEM、XRD及万能拉伸试验机,研究了Zn添加对其铸态组织和力学性能的影响。结果表明,Mg-10Gd-2Y-0.5Zr合金的铸态组织主要由α-Mg、Mg₅(Gd,Y)和Mg₂₄(Y,Gd)5相组成,而添加质量分数为0.5%~1.5%的Zn后,合金的铸态组织主要由α-Mg、Mg₅(Gd,Y,Zn)、Mg₂₄(Y,Gd,Zn)₅及Mg₁₂(Gd,Y)Zn相组成。添加0.5%的Zn后,合金的室温力学性能明显提高,当Zn含量高于1.0%后,镁合金的室温力学性能开始逐步降低。当Zn含量为0.5%时,合金具有较佳的综合力学性能,其抗拉强度、屈服强度和伸长率分别为197 MPa、160 MPa和4.37%。Zn对Mg-10Gd-2Y-0.5Zr合金铸态力学性能的影响与其铸态组织中Mg₅(Gd,Y,Zn)、Mg₂₄(Y,Gd,Zn)₅和Mg₁₂(Gd,Y)Zn第二相及其数量有关。     

挤压比及不同Mn含量对Mg-10Gd-6Y-1.6Zn-xMn镁合金组织性能的影响

通过模铸法制备了Mg-10Gd-6Y-1.6Zn-xMn (x=0.4, 0.8, 1.2, 1.6, 2.0, wt.%)系列镁合金,研究了挤压比及Mn含量对Mg-10Gd-6Y-1.6Zn-xMn镁合金显微组织及室温力学性能的影响。研究结果表明：铸态Mg-10Gd-6Y-1.6Zn-xMn合金经热挤压后,合金中的长周期堆垛有序(LPSO)结构由亚稳的18R结构转变为稳定的14H结构。大挤压比能够显著提高合金的室温力学性能,当Mn含量为0.8%时,未时效态抗拉强度达到386MPa,断后延伸率约为10%。     

Microstructures and mechanical properties of extruded Mg-1Mn-3.5Y and Mg-1Mn-1Y-2.5Nd alloys

Both Mg-1Mn-3.5Y and Mg-1Mn-1Y-2.5Nd alloys(mass fraction,%)were extruded at 380℃.Most of the(10 10) crystal planes in the Mg-1Mn-3.5Y alloy are parallel to the normal direction,while most of the(10 11)crystal planes in the Mg-1Mn-1Y-2.5Nd alloy are parallel to the normal direction.The tensile tests at room temperature,100℃ and 200℃ show that the Mg-1Mn-3.5Y alloy exhibits higher yield strength,but lower elongation to failure as compared with the Mg-1Mn-1Y-2.5Nd alloy. These differences in the tensile mechanical properties between the two alloys are mainly attributed to their different texture types and amount and distribution of the Mg24Y5 precipitates.The serration flow behavior is observed in the Mg-1Mn-1Y-2.5Nd alloy at 200℃,but does not occur in the Mg-1Mn-3.5Y alloy.The Mg-1Mn-3.5Y alloy shows the cleavage fracture mode,while the Mg-1Mn-1Y-2.5Nd alloy exhibits the dimple fracture mode.     

Effect of ageing treatment on microstructures,mechanical properties and corrosion behavior of Mg-Zn-RE-Zr alloy micro-alloyed with Ca and Sr

Effects of ageing treatment on the microstructures, mechanical properties and corrosion behavior of the Mg-4.2Zn-1.7RE-0.8Zr-xCa-ySr [x=0, 0.2 (wt.%), y=0, 0.1, 0.2, 0.4 (wt.%)] alloys were investigated. Results showed that Ca or/and Sr additions promoted the precipitation hardening behavior of Mg-4.2Zn-1.7RE-0.8Zr alloy and shortened the time to reaching peak hardness from 13 h to 12 h. The maximum hardness of 77.1±0.6 HV for the peak-aged Mg-4.2Zn-1.7RE-0.8Zr-0.2Ca-0.2Sr alloy was obtained. The microstructures of peak-aged alloys mainly consist of α-Mg phase, Mg₅₁Zn₂₀ phase and ternary T-phase. The Zn-Zr phase is formed within the α-Mg matrix, and the Mg₂Ca phase is formed near T-phase due to the enrichment of Ca in front of the solid-liquid interface. Furthermore, fine short rod-shaped β′₁ phase is precipitated within the α-Mg matrix in the peak-aged condition. The peak-aged Mg-4.2Zn-1.7RE-0.8Zr-0.2Ca-0.2Sr alloy exhibits optimal mechanical properties with an ultimate tensile strength of 208 MPa, yield strength of 150 MPa and elongation of 3.5%, which is mainly attributed to precipitation strengthening. In addition, corrosion properties of experimental alloys in the 3.5wt.% NaCl solution were studied by the electrochemical tests, weight loss, hydrogen evolution measurement and corrosion morphology observation. The results suggest that peak-aged alloys show reduced corrosion rates compared with the as-cast alloys, and minor additions of Ca and/or Sr improve the corrosion resistance of the Mg-4.2Zn-1.7RE-0.8Zr alloy. The peak-aged Mg-4.2Zn-1.7RE-0.8Zr-0.2Ca-0.2Sr alloy possesses the best corrosion resistance, which is mainly due to the continuous and compact barrier wall constructed by the homogeneous and continuous second phases.

     

Ce、Y和Gd对Mg-3Sn-2Sr镁合金铸态组织和力学性能的影响(英文)

通过扫描电镜、X射线衍射、差热分析以及抗拉和蠕变性能测试等手段,调查和比较了Ce、Y和Gd对Mg-3Sn-2Sr镁合金铸态组织和力学性能的影响。结果表明:Mg-3Sn-2Sr三元合金主要由?-Mg、初生和共晶SrMgSn以及Mg2Sn相组成。当添加1.0%Ce、1.0%Y和1.0%Gd到Mg-3Sn-2Sr合金后,合金中分别形成了Mg12Ce、YMgSn、GdMgSn和/或Mg17Sr2相。同时,合金中初生SrMgSn相的形成被抑制,且呈针状的粗大初生SrMgSn相也被变质和细化。此外,添加1.0%Ce、1.0%Y和1.0%Gd均能同时改善Mg-3Sn-2Sr合金的抗拉性能和蠕变性能。在含Ce、Y和Gd合金中,含Ce合金的抗拉性能相对较含Y和含Gd合金的高。     

Precipitation-hardened Mg–Ca–Zn alloys with superior creep resistance

The present paper reports the development of creep resistant Mg–Ca–Zn based alloys that can be strengthened via age hardening. The Mg–1Ca–1Zn–0.6Zr (wt.%) alloy shows tensile and creep properties superior to magnesium alloy AZ91. The addition of 1 wt.% Nd to this alloy leads to further improvements in yield strength and creep resistance.     

Influence of yttrium on microstructure and mechanical properties of as-cast Mg-5Li-3Al-2Zn alloy

The influence of Y on microstructure and mechanical properties of as-cast Mg-5Li-3Al-2Zn alloy was investigated. The results show that the phase compositions of Mg-5Li-3Al-2Zn consist of α-Mg and AlLi phases. Adding Y to the alloy results in the formation of Al₂Y compound and facilitates grain refinement. The addition of 0.8 wt.% Y produces the smallest grain size. The tensile tests performed at room temperature show that the additions of Y can improve the mechanical properties of the alloy; the tensile strength and ductility reach peak values when the Y additions are 0.8 wt.% and 1.2 wt.%, respectively. The mechanisms of improvement are related to grain refinement and compound strengthening effects.     

Zn含量对Mg-Gd-Zn合金显微组织与力学性能的影响

研究了3种成分的Mg-11Gd-(1,1.5,2)Zn合金的显微组织和力学性能。结果表明,合金的铸态显微组织均由α-Mg基体、(Mg,Zn)3Gd共晶相和14H型LPSO相组成。铸态组织中(Mg,Zn)3Gd相的体积分数随Zn含量的增加而增大,且其热稳定性不断提高。同时,合金中LPSO相的体积分数也随Zn含量的增加而逐渐增大。合金在常温时的抗拉强度随着Zn含量的增加而降低,其中Zn含量较少的Mg-11Gd-1Zn合金在T6处理后呈现最高的强度和良好的塑性。当Zn含量较多时,合金T6处理的效果却远低于T5处理。随Zn含量的增加,合金在200℃高温下的抗蠕变性能也略有下降,但3种合金的抗蠕变性能都优于WE54合金。     

热处理对砂型铸造Mg-4Y-2Nd-1Gd-0.4Zr镁合金显微组织和力学性能的影响(英文)

研究热处理工艺对砂型铸造Mg-4Y-2Nd-1Gd-0.4Zr镁合金显微组织和力学性能的影响,分析不同热处理条件下合金的断裂机制,获得最佳热处理工艺。结果表明:Mg–4Y–2Nd–1Gd–0.4Zr合金的最佳T4和T6热处理工艺分别为525°C,8 h和(525°C,8 h)+(225°C,16 h)。在最佳T6热处理条件下,Mg-4Y-2Nd-1Gd-0.4Zr合金的硬度、屈服强度、抗拉强度和伸长率分别为HV91、180 MPa、297 MPa和7.4%。此外,不同状态的Mg-4Y-2Nd-1Gd-0.4Zr镁合金也显示出不同的拉伸断裂方式。     

不同固溶状态Mg-10Gd-3Y-1.2Zn-0.5Zr合金的力学性能及断裂行为研究

通过在Mg-10Gd-3Y-0.5Zr合金中添加少量Zn制备出一种新型Mg-10Gd-3Y-1.2Zn-0.5Zr合金,并利用扫描电子显微镜、拉伸试验机分析研究Mg合金不同状态下的显微组织、力学性能及断裂行为。结果表明：Mg-10Gd-3Y-1.2Zn -0.5Zr合金在不同的时效状态下,铸态塑性差,T4态塑性好,T6态塑性优于铸态但劣于T4态,且所有样品都是脆性解理断裂为主,晶界和层状相界面比化合物界面结合牢固。通过比较3个不同温度下T6态的力学性能,发现提高固溶温度能提高合金的强度,但延伸率会略降。并且Zn促进层状相生长,但是对基体塑性提高作用有限。     

Effect of Minor Er on the Microstructure and Properties of Al-6.0Mg-0.4Mn-0.1Cr-0.1Zr Alloys

As-cast Al-6.0Mg-0.4Mn-0.1Cr-0.1Zr alloys containing different additions of Er were prepared. Then, the specimens were carried out homogenization heat treatment, hot rolling, cold rolling, and annealing. The effects of minor Er on the microstructure and properties of Al-6.0Mg-0.4Mn-0.1Cr-0.1Zr alloy were investigated. Results show that addition of Er can refine the microstructure and improve the mechanical properties of the alloys. As for the annealed alloys, the addition of 0.33%Er can increase the tensile strength by 29 MPa. Strength increment is mainly attributed to refinement and the precipitation of Al₃Er and Al₃(Er, Zr). Additionally, the minor Er can improve the corrosion resistance of the alloys, which can be attributed to the compact composite oxide film of Er-O and Al-O, purification, and modification.     

Mg-3Ce-1.2Mn-0.9Sc和Mg-3Ce-1.2Mn-1Zn镁合金铸态组织和力学性能的比较(英文)

比较研究了Mg-3Ce-1.2Mn-0.9Sc和Mg-3Ce-1.2Mn-1Zn镁合金的铸态组织和力学性能。结果表明:含Sc合金主要由α-Mg、Mg12Ce和Mn2Sc相组成,而含Zn合金则主要由α-Mg和Mg12Ce相组成。然而,含Sc和含Zn铸态合金中Mg12Ce相的形貌是不同的。含Sc合金中的Mg12Ce相主要呈颗粒状,而含Zn合金中的Mg12Ce相则主要呈连续和/或准连续的网状。同时,含Sc合金的晶粒较含Zn合金的相对较为细小。此外,虽然含Sc合金和Zn合金在室温和300°C下具有相似的抗拉性能,但含Sc合金在300°C和30MPa下持续100h后的抗蠕变性能较Zn合金的好。     

往复挤压对Mg-0.85Zn-0.15Y-0.6Zr铸态组织和力学性能的影响

研究了往复挤压对准晶增强Mg-0.85Zn-0.15Y-0.6Zr铸态合金显微组织及力学性能的影响。结果表明,往复挤压可大幅度细化Mg-0.85Zn-0.15Y-0.6Zr铸态合金组织,且使I相等相对均匀地分布在α-Mg基体中。同铸态合金相比,挤压后Mg-0.85Zn-0.15Y-0.6Zr合金的屈服强度、抗拉强度和延伸率分别提高了75.8%,43.2%和35%。     

Electrochemical Hydrogen Storage Characteristics of the as-Cast and Annealed La0.8-xPrxMg0.2Ni3.35Al0.1Si0.05 (x=0~0.4) Electrode Alloys

研究了Mg-3.8Zn-2.2Ca-xSn(x=0,0.5,1,2,质量分数%)镁合金的铸态组织、抗拉性能和蠕变性能。结果发现:在含Sn合金中会形成CaMgSn相,并且随着Sn含量从0.46%增加到1.88%(质量分数),合金中CaMgSn相的数量增加。同时,合金中Ca2Mg6Zn3相的形貌从最初的连续和/或半连续网状转变为半连续和/或断续状。此外,含Sn合金的晶粒被明显细化,其中含0.90%Sn合金的晶粒最细。与三元合金相比,含0.46%和0.90%Sn合金的抗拉性能和蠕变性能改善明显,而含1.88%Sn合金的屈服强度和蠕变性能虽然得到改善,但其抗拉强度和延伸率减小。在含0.46%、0.90%和1.88%Sn的3个合金中,含0.90%Sn的合金显示了优化的抗拉性能和蠕变性能。     

Zn元素对Mg-7Y-3Sm-0.5Zr合金显微组织和力学性能的影响(英文)

研究添加Zn元素对铸造Mg-7Y-3Sm-0.5Zr合金的显微观组织和力学性能的影响。蠕变测试的温度范围为200-300 °C,应力范围为50-120 MPa。在本研究的蠕变测试条件下,合金的蠕变激活能为156-221kJ/mol。采用光学显微镜、扫描电镜和透射电镜观察合金在蠕变过程中显微组织的演化。结果表明:尽管合金在250 °C以下有着相似的蠕变行为,仅添加1%的Zn元素就能使合金在300 °C和50MPa蠕变条件下的蠕变寿命从52.2h提高到152.8h,表明Zn元素能够提高合金的高温抗蠕变性能。加入Zn元素后,合金中形成的高温稳定相和片层状结构相是合金高温抗蠕变性能提高的根本原因。     

Effect of Sc and Sr on the Eutectic Si Morphology and Tensile Properties of Al-Si-Mg Alloy

To study the effect of Sc and Sr additions on modifying eutectic silicon particles and mechanical properties for Al-Si-Mg casting alloy, they were added with different amounts in F357 alloy without beryllium addition in the present work. It was found that (0.4 wt.% Sc and 0.04 wt.% Sr)-modified F357 alloy presented the optimal tensile properties when compared with the individual addition of Sc or Sr. This was mainly attributed to the synergic modification of eutectic Si in F357 alloys due to the combined additions of Sc and Sr. The silicon modification mechanisms via Sc and Sr were emphasized to be examined in this paper, and the fracture mechanism of the obtained alloys was also discussed.