Mn和Cr对6× × ×铝合金再结晶行为的影响

制备了不同Mn、Cr含量的Al-Mg-Si-Cu铝合金,合金经均匀化处理后,在Gleeble-3500热模拟试验机上进行不同温度的热压缩变形(压缩应变速率为1 s~(-1),变形量为70%)。试样径T6处理后,采用JSM-6480扫描电镜及图像处理软件,观察试样的截面处再结晶百分比及再结晶晶粒特征。结果表明:Al-Mg-Si-Cu合金的再结晶机理为二次再结晶。对于同一合金,热变形温度越高,未再结晶区域的面积比越高;在相同变形条件下,Mn和Cr含量越高,未再结晶区域的面积比越高,再结晶抑制效果越显著。但Mn和Cr含量越高,合金中粗大的第二相增多,将导致疲劳韧性等性能下降。因此,需综合各项性能考虑Mn和Cr的添加量。     

复合添加Cr、Mn、Zr对Al-Zn-Mg合金组织和性能的影响

通过光学显微镜、扫描电镜、透射电镜观察以及拉伸试验等手段,研究Cr、Mn、Zr微合金元素对Al-Zn-Mg合金组织和性能的影响。结果表明:复合添加Zr、Mn、Cr在基体上析出大量不规则的、直径为10~20 nm与基体共格的(Al,Cr)₃Zr粒子。(Al,Cr)₃Zr粒子弥散相能强烈钉扎位错、阻碍位错和亚晶界迁移,显著抑制再结晶和晶粒长大。复合添加Zr、Mn、Cr的Al-Zn-Mg合金的抗拉强度和规定塑性延伸强度分别提高34 MPa、19 MPa,具有较好的加工性能和力学性能。     

Cr、Mn、Zr、Ti微合金化对Al-Zn-Mg-Cu-Yb合金再结晶、第二相和断裂行为的影响（英文）

采用拉伸测试,结合TEM、SEM和EBSD等物相和微观结构表征,研究了单独添加Cr、Mn、Zr、Ti对Al-Zn-Mg-Cu-Yb合金中第二相(特别是AlCuYb相)析出、基体再结晶行为和拉伸沿晶断裂的影响。结果表明:在同时添加Yb和Cu的铝合金中,微米级、粗大AlCuYb相的析出难以避免。但有趣的是,进一步添加Mn的合金中,由于析出了亚微米的Al_(20)Cu_2Mn_3相,可有效减少粗大AlCuYb相,在4种合金中形成的粗大相的数量最少。Al-Zn-Mg-Cu-Yb合金中添加Zr可析出纳米级Al_3(Yb, Zr)弥散相,有效抑制结晶,但是AlCuYb相的形成消耗Yb元素,降低了二次共格Al3(Yb, Zr)弥散相的析出,此外粗大AlCuYb相颗粒诱发局部再结晶,一定程度降低了合金的强度。T6态AlZnMgCuYb-Zr和AlZnMgCuYb-Mn合金经固溶后仍保持未再结晶纤维状结构,小角度再结晶分数高达50%以上,平均晶粒尺寸降至2～7μm。相比之下,添加Cr或Ti的Al-Zn-Mg-Cu-Yb合金形成均匀再结晶晶粒,大角度再结晶分数高达80%,平均晶粒尺寸为40～96μm。断裂时,尺寸1～3μm的初生Al_2CuMg相(而非粗大AlCuYb相)优先诱发断裂,裂纹沿析出相连续、粗大且无沉淀析出相宽化的大角度再结晶晶界或原始晶界扩展。     

微量Cr、Mn、Zr、Ti、B元素对铸态AlZnMgCu合金的晶粒细化效果的影响

采用光学显微镜、扫描电镜和能谱分析仪考察了Cr、Mn、Zr、Ti、B的联合加入对AlZnMgCu合金的晶粒细化效果。结果发现在铸态合金中同时加入Cr-Mn-Ti-B时晶粒尺寸由256 μm 降为102 μm。而当联合加入Ti-Zr-B后能产生更加强的细化效果,晶粒平均尺寸降为55 μm。这是因为Cr、Mn原子簇团有利于促进Al3Ti形核并成为其结晶基底。当联合加入Cr、Mn、Zr、Ti、B时则可产生更加明显的晶粒细化效果,平均晶粒尺寸变为22 μm。这是因为富Cr、Mn原子簇团在成为Al3Ti结晶核心后,部分Zr原子置换了其中的Ti原子形成了新的Al3(Tix, Zr1-x)结晶核心。而过渡族金属Cr、Mn还能降低液体金属和Al3Ti和Al3(Tix, Zr1-x)的表面张力,抑制结晶核心的长大。     

稀土Nd对AZ31变形镁合金组织与性能的影响

研究在AZ31B变形镁合金中添加稀土Nd对AZ31B合金铸态和热轧退火态性能及组织的影响。结果表明:在AZ31B变形镁合金中添加Nd后,合金的铸态和热轧退火态的室温抗拉强度和伸长率均降低;加入的Nd与Al形成Al2Nd相,Nd还可以与Al和Mn形成Al-Nd-Mn化合物,剩余的Al还可以和Mg形成Mg17Al12相。含Al和Mn的金属间化合物削弱元素Al、Mn对镁合金的晶粒细化作用导致晶粒粗大,进而降低铸态AZ31B合金性能;热稳定性好的粗大第二相的出现也是导致合金铸态性能降低的原因,增大变形量使第二相得到充分破碎,会使板材力学性能得到改善。     

Al—Mg—Si—Mn—Cr合金的显微组织与拉伸性能

研究了微量Mn和Cr对Al-Mg-Si合金显微组织和拉伸性能的影响。结果表明：在AL-Mg-Si合金中同时添加微量Mn和Cr,可形成含Mn、Cr的弥散 出相,阻止合金的再结晶,使合金挤压后纤维状组织;均匀化处理可使Mg2Si溶及针状β－AlFeSi相转化为粒状α－AlFeSi相;同时有利于细小时效析出相的析出,从而提高合金的强度。     

Mn对Al-Mg-Si-Cu铝合金结晶相的影响

通过扫描电镜/能谱、 X射线衍射以及金相分析, 针对含0.3?(质量分数)的Al-Mg-Si-Cu铝合金, 研究了Mn含量对其结晶相的影响. 研究表明: 合金在铸造过程中形成的结晶相为Al1.9CuMg4.1Si3.3, Al5(FeMn)Si, Al8(FeMn)2Si以及少量的Mg2Si; 增大含Mn量, 合金中AlFeMnSi型结晶相数量增多; 对合金进行均匀化处理时, Al1.9CuMg4.1Si3.3相完全溶解, 发生Al5(FeMn)Si向Al8(FeMn)2Si相的转变; 对合金进行轧制及最终热处理后, 结晶相碎化且沿轧向呈纤维状分布, 但结晶相的类型不变.     

Er对铸态Mg-Al-Zn-Mn合金组织与力学性能的影响

通过熔炼铸造法制备了不同Er含量的铸态Mg-9．0Al-0．8Zn-0．15Mn合金。采用X射线衍射、金相观察、扫描电镜及拉伸性能测试，研究了Er的添加对合金的显微组织与力学性能影响。结果显示，基体合金中添加Er后，显微组织主要由α-Mg相、Mg17Al12相及Al3Er相组成。添加Er元素能有效细化铸态合金的晶粒，使其平均晶粒尺寸从57μm降低到21μm；同时Er的添加改善了基体合金中Mg17Al12相的形态与分布，最终使基体合金的室温抗拉强度得到提高。     

单独或复合添加Al-5Ti-B、Mn和Sn对A356铝合金滑动磨损性能的影响(英文)

研究添加Al-5Ti-B、Mn和Sn对A356铝合金滑动磨损性能的影响。采用光学显微镜、扫描电镜和透射电镜观察合金的显微组织和磨损表面。结果表明,Al-5Ti-B晶粒细化的合金具有α(Al)等轴晶组织,比未细化合金具有更好的抗磨损性能。另外,Mn元素的添加能使β-Al5Fe Si转变成α-Al(Mn,Fe)Si相,减少裂纹形成的倾向并提高合金的抗磨损性能。A356合金中添加Sn会形成Mg2Sn相,导致合金不能形成Mg2Si析出强化相;同时软化的β-Sn相会降低合金的硬度并最终降低合金的抗磨损性能。     

Cr、Mn、Zr、Ti微合金化对Al-Zn-Mg-Cu-Yb合金再结晶、第二相和断裂行为的影响

采用拉伸测试,结合XRD、TEM、SEM和EBSD等物相和微观结构表征,研究了单独添加Cr、Mn、Zr、Ti对Al-Zn-Mg-Cu-Yb合金第二相(特别是AlCuYb相)析出、基体再结晶行为和拉伸沿晶断裂的影响。研究结果表明：在同时添加Yb和Cu的铝合金中,微米级、粗大AlCuYb相的析出难以避免。但有趣的是,进一步添加Mn的合金中,由于析出了亚微米的Al₂₀Cu₂Mn₃相,可有效减少粗大AlCuYb相,在四种合金中形成的粗大相的数量最少。Al-Zn-Mg-Cu-Yb合金中添加Zr,可析出纳米级 Al₃(Yb, Zr)弥散相,有效抑制结晶,但是AlCuYb相的形成消耗Yb元素,降低了二次共格Al₃(Yb, Zr)弥散相的析出,此外粗大AlCuYb相颗粒诱发局部再结晶,一定程度降低了合金的强度。T6态 Al-Zn-Mg-Cu-Yb-Zr和Al-Zn-Mg-Cu-Yb-Mn合金经固溶后仍保持未再结晶纤维状结构,小角度再结晶分数高达50%以上,平均晶粒尺寸降至2~7 μm。相比之下,添加Cr或Ti的Al-Zn-Mg-Cu-Yb合金形成的均匀的再结晶晶粒,大角度再结晶分数高达80%,平均晶粒尺寸为40-96 μm。断裂时,尺寸1~3 μm的初生Al₂CuMg相(而非粗大AlCuYb相)优先诱发断裂,裂纹沿析出相连续、粗大且无沉淀析出相宽化的大角度再结晶晶界或原始晶界扩展。     

Synergistic effect of Ni and N on improvement of pitting corrosion resistance of high nitrogen stainless steels

Abstract

The pitting corrosion resistance of Fe18Cr10Mn(0·33–0·69)N, Fe18Cr10Mn1Ni(0·33–0·84)N, and Fe18Cr10Mn0·35N(0–3)Ni alloys were investigated. The pitting potential increased as the N content increased in both Fe18Cr10Mn(0·33–0·69)N and Fe18Cr10Mn1Ni(0·33–0·84)N alloys. The rise in the pitting potential was more pronounced in Fe18Cr10Mn1Ni(0·33–0·84)N alloys than in Fe18Cr10Mn(0·33–0·69)N alloys. However, it was found that Ni alone had no effect on the pitting corrosion resistance of Fe18Cr10Mn0·35N based alloys. Thus, it was concluded that the alloyed N worked synergistically with Ni to promote the pitting corrosion resistance in Fe18Cr10Mn based alloys. Analyses of passive films of Fe18Cr10Mn(0·33–0·69)N and Fe18Cr10Mn1Ni(0·33–0·84)N alloys revealed that N was incorporated into the passive film, with N enriched at the film/metal interface. However, the alloyed N increased the Cr cation fraction in passive films of Fe18Cr10Mn1Ni(0·33–0·84)N alloys, whereas N decreased in that of Fe18Cr10Mn(0·33–0·69)N alloys. This difference was considered as the reason for the synergistic effect between N and Ni in Fe18Cr10Mn based alloys.     

The effects of addition of deoxidation elements on the morphology of (Mn,Cr)S inclusions in stainless steel

The effects of additions of C, Si, Ti, and Al on the morphology of (Mn,Cr)S inclusions in Fe-15Cr-1Mn-0.3S (mass%) and Fe-15Cr-0.5Mn-0.3S base alloys have been investigated using optical and scanning electron microscopy. Three types of (Mn,Cr)S inclusions morphology have been observed (1) globular-shaped sulfide, (2) rodlike (Mn,Cr)S, and (3) angular (Mn,Cr)S, depending on the Mn content and the presence of additional elements. The formation mechanisms of (Mn,Cr)S inclusions are discussed on the basis of phase diagram information. It is shown that (a) the globular (Mn,Cr)S inclusions observed in 1% Mn alloys are formed through the metastable monotectic reaction, (b) the rodlike (Mn,Cr)S observed on the addition of Ti and Al are the products of a stable eutectic reaction that proceeds by nucleation of (Mn,Cr)S crystals by the high-melting-point particles such as TiN and Al₂O₃, (c) the globular (Mn,Cr)S morphology observed in 0.5% Mn base alloys is the result of a stable monotectic reaction that proceeds through the formation of the low-melting globular (Mn,Cr)S inclusions, and (d) the addition of C and Si promote the stable eutectic reaction by lowering the melting point of Fe-rich solid solution.     

Comparison of shape memory effect between casting and forged alloys of Fe14Mn6Si9Cr5Ni

The effect of different manufacturing techniques on the shape memory effect (SME) of the Fe14Mn6Si9Cr5Ni alloy has been studied. The SMEs of casting and forged alloys are similar. At ambient temperature, creep and stress-relaxation experiments of the casting alloy show that the casting alloy presents a good creep rupture strength. The manufactured pipe joints of the casting alloys keep jointing under a tensile force of 20 kN and keep sealing under a pressure of 5 MPa. Those excellent mechanical properties satisfy the requirements for pipe jointing in general industrial applications.     

Diffusion behaviour of hydrogen in nitrogen containing austenitic alloys

Electrochemical permeation technique and thermal desorption spectroscopy were used to evaluate the hydrogen diffusion, solubility, and trapping behaviour in nitrogen containing austenitic alloys. The hydrogen diffusion of all alloys obeyed Arrhenius relationships in the studied experimental temperature range. The apparent diffusion coefficients were determined and the relevant activation energies were estimated. Nitrogen at higher concentration (>0.38 wt.%) as well as chromium decrease the hydrogen diffusion whereas nickel has opposite effect. The thermal analysis of all alloys except Cr18Mn18N0.57 shows a main single peak at different heating rates indicating no significant hydrogen interaction with microstructural defects. The alloy Cr18Mn18N shows a shoulder in addition to the peak which is attributed to nitrogen–hydrogen interaction. The activation energy estimated from the thermal analysis is nearly equal to the activation energy for diffusion obtained from the Arrhenius plots of the corresponding alloys.     

Ti0.9Zr0.2Mn（1.8—x）MxV0.2（M=Ni,Cr;x=0,0.2）合金的贮氢性能

研究了Ti0.9Zr0.2Mn(1.8-x)MxV0.2(M=Ni,Cr;x=0,0.2)合金的晶体结构与贮氢性能。结果表明,Ti0.9Zr0.2Mn1.6Ni0.2V0.2和Ti0.9Zr0.2Mn1.6Cr0.2V0.2的贮氢量达到240mL/g。合金的主相均为C14 Laves相,镍,铬的取代使点阵常数和晶胞体积增大,P－C－T曲线的滞后降低,压力平台的倾斜度增加。     

The Effect of Alloying Elements on the Microstructure of Al-5Fe Alloys

The effects of adding Cr, Mn, and Zr on the microstructure of Al-5Fe alloys has been studied by metallographic analysis, scanning electron microscopy, x-ray diffraction analysis, and differential thermal analysis. It has been found that the effects of the different elements on the microstructure of ferro-aluminum intermetallics in Al-5Fe alloys are not alike. Addition of Cr in Al-5Fe alloys dissolves only into AlFe intermetallics, resulting in the morphology of the AlFe phases being changed with increasing Cr content. Cr is a favorable nucleating agent for encouraging metastable Al _x Fe (x = 4.6 to 5.0) phase formation. Adding Mn in Al-5Fe alloys may stabilize the metastable Al₆Fe phase, helping the primary phase field of Al₇Cr diminish or even disappear and forcing Cr to dissolve into AlFe phases. Adding Zr does not refine the primary AlFe intermetallics. Al₃Zr particles in Al-5Fe alloys will occupy the growing spaces of ferro-aluminum phases and indirectly hinder the growth of Fe-bearing phases.     

MICROSTRUCTURE AND COMPRESSIVE PROPERTIES OFTi_(50)Al_(48)Mn_2 AND Ti_(50)Al_(48)Cr_2

The microstructure and compressive properties of Ti_(500Al_(48)Mn_2and Ti_(50)Al_(48)Cr_2 alloys are studied in this paper Existence of αx y transforntation in TiAl alloys is confirnted by metallographic examincttion,the transformation temperatuses of Ti_(50)Al_(48)Mn_2 and Ti_(500Al_(48)Cr_2,are 1375and 1373C respeclively,After treating withic x y phase field,themicrostructure of alloys consists of lamellar zones(L)and bulk y_p.,The vohme ratio of L/y_p inctrases with increasing solution treatnient temperature.The third alloying ele-ments of Mn and Cr distribute perfentially over αphase at solution treatment tempera-tures and result in that α_2 and γ lamellae become thicker.The yield strength of Ti_(50)Al_(48)Mn_2 and Ti_(500Al_(48)Cr_2 alloys decreases and the compressibllity increases with in-creasing γ_p volume fraction.     

Effects of cerium and manganese on corrosion of Fe–Cr and Fe–Cr–Ni alloys in Ar–20CO2 gas at 818 °C

Model alloys Fe–9Cr, Fe–20Cr and Fe–20Cr–20Ni (wt.%) with Ce (0.05%, 0.1%) or Mn (1%, 2%) were exposed to Ar–20CO₂ gas at 818 °C. Scales on Fe–9Cr alloys consisted of FeO and FeCr₂O₄, Fe–20Cr–(Ce) alloys formed only Cr₂O₃, and Fe–20Cr–(Mn) alloys formed Cr₂O₃ and MnCr₂O₄. All Fe–20Cr–20Ni alloys formed Fe₃O₄, FeCr₂O₄ and FeNi₃. Cerium additions had little effects, but additions of 2% Mn significantly improved oxidation resistance of Fe–20Cr and Fe–20Cr–20Ni alloys. Most alloys also carburized. All alloys developed protective chromium-rich oxide scales in air. Different behavior in the two gases is attributed to faster Cr₂O₃ scaling rates induced by CO₂.     

Effect of N and C on stress corrosion cracking susceptibility of austenitic Fe18Cr10Mn-based stainless steels

Stress corrosion cracking (SCC) susceptibility of austenitic Fe18Cr10Mn alloys with 0.3N, 0.6N and 0.3N0.3C was investigated in aqueous chloride environment using a slow strain rate test method. The SCC susceptibility of Fe18Cr10Mn alloys in 2 M NaCl solution at 50 °C under constant anodic potential condition decreased with increase in N content from 0.3 to 0.6 wt%, and with addition of 0.3 wt% C to the Fe18Cr10Mn0.3N alloys. The present study strongly suggested that the beneficial effects of N and C on the SCC behavior of Fe18Cr10Mn alloys would be associated with the resistance to pitting corrosion initiation and the repassivation kinetics.