Microstructure and mechanical properties of ZA62 based magnesium alloys with calcium addition

As-cast microstructure and mechanical properties of Mg-6Zn-2Al-0.3Mn (ZA62) alloys with calcium addition were investigated.The as-cast microstructure of the base alloy ZA62 consists of the α-Mg matrix and eutectic phase Mg51Zn20.The Mg51Zn20 eutectic was gradually replaced by MgZn phase and Mg32(Al,Zn)49 phase when calcium is added into the base alloy.Further addition of calcium leads to the increase of grain boundary phases and formation of a new quaternary Mg-Zn-Al-Ca eutectic compound.In comparison with the base alloy,the increase of calcium addition to the base alloy results in the reduction of both strength and ductility at ambient temperature,but increase at elevated temperatures due to the thermal stability of Ca-containing phases.At elevated temperatures,the creep resistance of ZA62 based alloys containing calcium is significantly higher than that of AZ91 which is the most commonly used magnesium alloy.     

High temperature creep property of silicon particles reinforced high Al Zn-based alloys

１　ＩＮＴＲＯＤＵＣＴＩＯＮＺｉｎｃｂａｓｅｄｃａｓｔａｌｌｏｙｓｃｏｎｔａｉｎｉｎｇａｈｉｇｈｃｏｎｃｅｎｔｒａｔｉｏｎｏｆａｌｕｍｉｎｕｍａｎｄｓｏｍｅｃｏｐｐｅｒｈａｖｅｂｅｅｎｆｏｕｎｄｔｏｂｅｅｃｏｎｏｍｉｃａｌａｎｄｅｆｆｅｃｔｉｖｅｆｏｒｓｕｂｓｔｉｔｕｔｅｓｆｏｒｂｒｏｎｚｅｉｎａｖａｒｉｅｔｙｏｆｇｅｎｅｒａｌｅｎｇｉｎｅｅｒｉｎｇｗｉｔｈｔｈｅｉｒｅｘｃｅｌｌｅｎｔｃｏｍｐｒｅｈｅｎｓｉｖｅｍｅｃｈａｎｉｃａｌｐｒｏｐｅｒｔｉｅｓａｎｄｗｅａｒｒｅｓｉｓｔａｎｃｅ…     

Microstructure and high temperature tensile properties of Al–Si–Cu–Mn–Fe alloys prepared by semi-solid thixoforming

The differences in the microstructure and elevated temperature tensile properties of gravity die cast, squeeze cast, and semi-solid thixoformed Al–Si–Cu–Mn–Fe alloys after thermal exposure at 300 °C were discussed. The results demonstrate that the elevated temperature tensile properties of semi-solid thixoformed alloys were significantly higher than those of gravity die cast and squeeze cast alloys, especially after thermal exposure for 100 h. The ultimate tensile strength (UTS) of semi-solid thixoformed alloys after thermal exposure at 300 °C for 0.5, 10 and 100 h were 181, 122 and 110 MPa, respectively. The UTS values of semi-solid thixoformed alloys were higher than those of heat resistant aluminum alloys used in commercial applications. The enhanced elevated temperature tensile properties of semi-solid thixoformed experimental alloys after thermal exposure can be attributed to the combined reinforcement of precipitation strengthening and grain boundary strengthening due to thermally stable intermetallic phases as well as suitable grain size.     

Diffusion pressure welding of NiAl and Ni3Al-based alloys with St3S steel

Alloys containing phases on intermetallic structures, known as intermetallic compounds, belong to the new generation of metallic materials which possess properties lying between those of metals and ceramics. They are alloys of two or more metals which have crystalline structures that are different from those of the crystalline structures of individual component metals. For a number of years, intermetallic compounds were regarded as useful when they appeared as dispersed phases in conventional alloys, but in many situations, for example in the bonding of ceramics with metals, such phases are undesirable because of their brittleness. However, as the knowledge of their unique properties, especially of their behaviour at elevated temperatures and in hostile environments increases, the idea of using this group of materials for constructional purposes has been born. Systems containing intermetallic compounds had been investigated and it was shown that a new and unique group of alloys can be created by combining the matrices of nickel, iron and titanium with that of aluminium.     

Si含量对Mg-8Zn-4Al-0.3Mn镁合金时效过程的影响

采用光学显微镜、扫描电镜(附EDAX能量分散光谱系统)和差示扫描量热仪(DSC)等分析手段研究了不同Si含量(0～1.61wt%)对Mg-8Zn-4Al-0.3Mn(ZA84)合金时效过程的影响。结果表明,合金经固溶处理后显微硬度较铸态下提高了8%左右,其Mg2Si、τ(Mg32(Al,Zn)49)等相基本未溶入基体中。随着ZA84合金中加入Si量的增加,合金的析出相形成激活能呈增加趋势,峰值时效时间由ZA84合金的2h左右推迟至8h左右,析出相粗化时间较ZA84合金推迟4h以上。合金中加入不同含量Si后其峰值时效显微硬度提高幅度为4%～12%。     

Ce对Zn-Al合金组织性能的影响

研究了Ｃｅ对ＺｎＡｌ合金（ＺＡ２７、ＺＡ４３）的力学性能、淬火时效特性及耐磨性的影响。结果表明,Ｃｅ能明显细化合金的铸态组织,提高其强度和塑性。当ＺＡ２７和ＺＡ４３中含Ｃｅ量分别为０．１０％和０．１５％时,获得最佳的力学性能。提出了Ｃｅ细化ＺｎＡｌ合金的机理,加Ｃｅ后成分过冷效应所引起的枝晶熔断脱落对细化α相起主要作用。     

AlP变质Si合金化ZA84合金的组织及力学性能

借助光学显微镜和JEM-2000FX透射电子显微镜(配备OXFORD ISIS EDXS附件)等分析手段,研究了AlP变质Si合金化ZA84合金的组织及力学性能。结果表明,ZA84合金、Si合金化ZA84(S1)合金及AlP变质Si合金化ZA84(P01)合金经固溶处理后,其Mg2Si及τ相的尖锐棱角变钝。ZA84合金的峰值时效时间在2 h,其纳米级的析出相沿基体α-Mg的(0001)密排面的[1010]晶向析出,而S1及P01合金的峰值时效时间推迟至8 h左右,其纳米级的析出相无取向分布。合金的析出机制均为连续析出。ZA84合金通过Si合金化、AlP对组织的变质和细化以及合金热处理,其力学性能得到了显著提高。     

Effect of Small Amount of Manganese on the Interdiffusivities in Fe-Al Alloys

The ability to weld aluminum and steel sheets depends strongly on the formation of intermetallic phases; a process that is, in turn, controlled by the interdiffusion of iron and aluminum across the welded interface. Understanding the interdiffusion behavior, and how it is influenced by tertiary elements such as manganese, will allow for better prediction of the properties of the spot weld. Hence, interdiffusion coefficients and activation energies for interdiffusion were determined in the α solid solution and B2 intermetallic phases of Fe-Al alloys in the presence of 1.5-2 at.% manganese with pseudo-binary diffusion couples investigated at 900-1095 °C. The interdiffusion coefficients in α were found to increase in the presence of Mn at all temperatures compared with those reported in the binary Fe-Al alloys. The activation energies for interdiffusion in α are correspondingly lower than those in the binary Fe-Al alloys. The increase in the main interdiffusion coefficients in the presence of Mn indicates that diffusional interactions between Fe and Al are increased in the presence of Mn. The expected increase in diffusional interactions of Fe and Al are found to be consistent with the thermodynamic interactions between Fe and Al in the binary Fe-Al and ternary Fe-Al-Mn system as estimated from the literature. The presence of Mn is found to decrease the solubility of Al in the α solid solution, which, in turn, is expected to decrease the growth rate of the intermetallic at the interface between steel and aluminum.     

铝含量对高铝锌基合金性能的影响

研究了Al≥27％的四种高Al锌基合金的组织和性能。由XRD衍射表明：高Al锌基合金的组织由α相、η相及ε相组成,随Al含量的提高,α相、η相细化,其中ZA40合金的抗拉强度及硬度最高,摩擦力矩、摩擦系数最小,在载荷800N和1100N下其耐磨性比ZA27分别提高了36．5％和69．2％。     

MICROSTRUCTURE ANALYSIS AND MECHANICAL PROPERTIES OF Zn—Al ALLOY ROD PRODUCED BY HEATED MOLD CONTINUOUS CASTING

The new technology of continuous casting by heated mold was used to produce directional solidification ZA alloy lines to eliminate the inter defects of these lines and increase their mechanical properties. The results are as follows: (1) The microstruc-ture of the ZA alloy lines is the parallel directional dendritic columnar crystal. Every dendritic crystal of eutectic alloy ZA5 was composed of many layer eutectic β and η phases. The micro structure of hypereutectic ZA alloys is primary dendritic crystal and interdendritic eutectic structure. The primary phase of ZA8 and ZA12 is β, among them, but the primary phase of ZA22 and ZA27 is a. (2) Through the test to the as-cast ZA alloy lines made in continuous casting by heated mold, it is found that the tensile strength and hardness increase greatly, but the elongation decreases. With the increase of aluminum amount from ZA 5 to ZA 12, ZA22 and ZA27, the tensile strength increases gradually. ZA27 has the best comprehensive mechanical properties in these     

Ce对ZA43合金组织与力学性能的影响

研究了稀土Ce加入量对ZA43合金铸态组织与力学性能的影响。结果表明,Ce能够细化ZA43合金的铸态组织。随Ce加入量增加,α相由发达的树枝晶转变为碎块状晶粒,ZA43合金的力学性能、耐磨性得到不同程度的改善,Ce元素主要分布于晶界,并以金属间化合物形式存在。综合考虑稀土Ce对ZA43合金组织及性能的影响,添加0.15%的Ce对提高ZA43合金综合力学性能最为有效。     

INFLUENCE OF CERIUM CONTENT ON DAMPING CAPACITIES OF AS-SPRAY DEPOSITED HIGH SILICON ALLOY ZA27

ＩＮＦＬＵＥＮＣＥＯＦＣＥＲＩＵＭＣＯＮＴＥＮＴＯＮＤＡＭＰＩＮＧＣＡＰＡＣＩＴＩＥＳＯＦＡＳＳＰＲＡＹＤＥＰＯＳＩＴＥＤＨＩＧＨＳＩＬＩＣＯＮＡＬＬＯＹＺＡ２７①ＬｉｕＹｏｎｇｃｈａｎｇ，ＬｕＹｉｌｉ，ＹａｎｇＧｅｎｃａｎｇ，ＺｈｕＺｈｅｎｇａｎ...     

ZA35合金在NaCl水溶液中的电化学行为

为了对合金元素Mn如何影响ZA35合金的电化学腐蚀性能有更深的认识,采用动电位极化方法测试了铸态ZA35和1．0％Mn．ZA35合金在不同温度的NaCl水溶液中的开路电位和极化曲线,分析了温度和合金元素Mn对合金电化学腐蚀性能的影响。实验结果显示：随着NaCl溶液温度升高,合金的开路电位下降（负移）,并且1．0％Mn．ZA35合金较铸态ZA35的开路电位低;NaCl溶液温度升高,铸态ZA35合金和1．0％Mn—ZA35合金腐蚀电流密度逐渐增加;相同温度下,1．0％Mn—ZA35合金较铸态ZA35合金腐蚀电流密度大。Mn做为合金元素,在ZA35合金基体中固溶度很小．1．0％Mn-ZA35合金中析出富锰相,降低了耐腐蚀性能。     

锰元素对锌基硅相复合材料性能的影响

研究了在硅相球化的ZA27、ZA35及ZA45合金中加入不同量的Mn时，对ZA合金硬度及耐磨性的变化规律。结果表明：在ZA27合金中Mn的加入量对其综合性能影响不大；在ZA35合金中锰的加入量为0.5％时。材料的综合性能较好；在ZA45合金中Mn的加入量≤1.0％时，其综合性能比较好。     

Effect of Mg-based spherical quasicrystal on microstructures and mechanical properties of ZA54 alloy

To improve the strength,toughness and heat-resistance of magnesium alloy,the microstructure and mechanical properties of ZA54 alloy reinforced by icosahedral quasicrystal phase(I-phase) particles were studied.Exceptα-Mg,φ-phase andτ-phase,MgZnYMn I-phase particles can be obtained in ZA54-based composites by the addition of icosahedral quasicrystal-contained Mg-Zn-Y-Mn master alloy.The introduction of MgZnYMn I-phase into ZA54 alloy has great contribution to the refinement of matrix microstructures and the improvement of mechanical properties.When the addition of Mg-based spherical quasicrystal master alloy is up to 3.5%(mass fraction) ,the macro-hardness of ZA54-based composites is increased to HB 68.The impact toughness of composites reaches the peak value of 18.3 J/cm2,which is about 29%higher than that of ZA54 mother alloy.The highest tensile properties at ambient and elevated temperatures with master alloy addition of 2.5%(473 K) are also obtained in ZA54-based composites with 3.5%(mass fraction) Mg-Zn-Y-Mn master alloy addition.The ultimate tensile strength of composites at ambient and elevated temperatures are 192.5 MPa and 174 MPa,which are 23.4%and 33.8%higher than that of ZA54 mother alloy,respectively. The improved mechanical properties are mainly attributed to the pinning effect of I-phase on grain boundaries.     

Ca、Y改性的Mg-2Zn-1Al镁合金腐蚀行为

采用扫描电镜、XRD、析氢及电化学测试等对0.2%Ca、0.2%Y改性的Mg-2Zn-1Al （ZA21）轧制板材的微观组织和腐蚀行为进行了分析。结果表明,Ca和Y细化了晶粒,改变了第二相类型,降低了含Mn相中锰含量。在3.5%NaCl溶液中,优先腐蚀位点位于含Mn相附近的镁基体上,12 h腐蚀速率满足：ZA21 (8.59 mm/a)>ZA21+0.2%Ca (7.17 mm/a)>ZA21+0.2%Y (4.22 mm/a)>ZA21+0.2%Ca+0.2%Y (1.26 mm/a)。耐蚀性提升可归因于晶粒的细化;高Mn相消失,低Mn相和无Mn相生成导致微电偶腐蚀减弱;Mg、 Mg(OH)₂、Ca₃Al₂O₆·xH₂O、CaY₄O₇和Y₂O₃组成的更致密、裂纹更浅、保护性更强的腐蚀产物膜替代了由Mg和Mg(OH)₂组成的充满裂纹、保护作用有限的腐蚀产物膜。     

Corrosion behaviour of thixoformed and heat-treated ZA27 alloys in NaCl solution

The influence of corrosion on the microstructure of thixoformed and heat-treated ZA27 alloys was investigated. The microstructure of ZA27 alloy was affected by heat treatment. The process of electrochemical corrosion occurs in both ZA27 alloys through the area of η phase. According to the results of immersion test and electrochemical measurements, the corrosion rate of the thixoformed ZA27 alloy is at least 50% lower than that of the thixoformed and thermally processed alloy. This indicates the unfavourable influence of applied heat treatment (T4 regime) on the corrosion resistance of the thixoformed ZA27 alloy.     

An Analysis of Selected Properties of ZA Alloys

Zinc-aluminum (ZA) alloys are a relatively new family of zinc foundry alloys having superior melting and casting characteristics and attractive mechanical properties. The ZA-8 and ZA-12 alloys are moderate to high strength materials while ZA-27 is a high-strength alloy. All can be sand cast, permanent molded and pressure die cast. An extensive characterization program is being implemented to develop appropriate and reliable engineering data for designers. Property development in all aspects of ZA metallurgy is welladvanced. The data available on selected physical and mechanical properties of ZA alloys is compared here with the properties of traditional casting alloys.     

SiCp颗粒复合对ZA27合金耐磨性能的影响

用铸造法制备了ＳｉＣｐ／ＺＡ２７复合材料,用ＭＭ２００磨损试验机,测定和对比了基体合金和不同颗粒含量复合材料在不同载重下的磨损量。结果表明：在重载条件下,复合材料的耐磨性远高于基体材料。     

ZA27纺锭锭底失效原因分析

研究铸造锌铝合金ZA27与锡青铜QSn6.5-0.1的摩擦磨损性能.发现在相同条件下ZA27合金的耐磨性好于锡青铜QSn6.5-0.1,但用ZA27合金制作的纺锭锭底却不如用QSn6.5-0.1制作的耐用,其原因是ZA27合金在凝固过程中产生的组织缩松,在润滑条件下进行磨损试验时,容易使润滑油及磨损中产生的粉末填入其中,从而影响了磨损实验的准确性.