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| 1 | Sn对制备具有纳米晶fcc结构钛基合金的影响显示文摘研究Sn含量对Ti-13Ta-xSn(x=3,6,9,12,摩尔分数,%)合金中fcc相形成的影响。合金采用机械合金化方法制备,所用设备为行星式球磨机。通过Rietveld分析发现,fcc相的晶粒尺寸小于10 nm,微应变大于10-3,这两个条件是钛基合金中形成fcc相所必需的。对于所有的样品,fcc相的显微组织中均含有小于10 nm的等轴晶。当Sn含量为6%时,钛合金中fcc相的含量最大,因为该合金具有最大的微应变(1.5×10-2)和晶粒尺寸(6.5 nm)。实验数据表明,球磨过程中形成固溶体和非晶相。用扩展Miedema模型对促进固溶体和非晶相形成的必要条件进行热力学计算。结果表明,当Sn含量从3%增加到12%时,形成非晶相所需的能量从大约10 k J/mol变为-5 k J/mol左右。热力学计算结果与XRD分析和HRTEM结果一致。 | C.AGUILAR E.PIO A.MEDINA C.PARRA R.MANGALARAJA P.MARTIN I.ALFONSO K.TELLO | 2020 | Transactions of Nonferrous Metals Society of China2020，30，8： | 2 |
| 2 | Effect of the initial ECAP passes on crystal texture and residual stresses of 5083 aluminum alloy显示文摘To produce a highly refined microstructure,several metals or alloys have been processed via equal-channel angular pressing(ECAP).In this work,the mechanical and microstructural changes of the 5083 aluminum alloy in H11 condition after processed by two ECAP passes were investigated.An ECAP H13 steel die with an inner angle(α)of 120°and outer curvature(β)of 20°was used.The microstructural changes were associated with the loss of texture symmetry.The morphologies of the Mg2Si andα-Al(Mn,Fe)Si precipitates for the sample at the initial condition were similar to those subjected to two ECAP passes.The peak broadening measured by X-ray diffraction revealed an increment of both grain refinement and microstrain.After the second extrusion pass,the hardness increased by 62%compared with the initial condition.Moreover,the heterogeneous hardness behavior was compatible with a highly localized dislocation density.After two ECAP passes,shear parallel bands were observed to be at nearly 45°to the extrusion direction.The evaluation of first-order residual stress as a function of the depth of the analyzed sample displayed compressive or tensile values,depending on the measured face.With the plastic deformation applied,the first and second-order residual stresses exhibited significant increment.Williamson-Hall plots showed positive slopes,indicating an increment in the microstrain. | L.Romero-Reséndiz A.Flores-Rivera I.A.Figueroa C.Braham C.Reyes-Ruiz I.Alfonso G.González | 2020 | International Journal of Minerals,Metallurgy and Materials2020，27，6： | 2 |
| 3 | Enantioselective Enzymatic Desymmetrizations in Organic Synthesis显示文摘 | E.Garcia-Urdiales I.Alfonso V.Gotor | | 0，，1： | 1 |
| 4 | Hardness-Lattice Parameter Correlation for Aged Al-Zn-Mg Alloys显示文摘Two ternary Al-2.2Zn-0.95Mg and Al-5.5Zn-2.1Mg(in wt pct) alloys,with Zn:Mg ratios close to 2.5 were produced by conventional ingot casting metallurgy.The ingots were solution heat treated at 500℃ for 0.5 h and aged at 180℃ for times between 0.5 and 80 h.The structural characterization was carried out by X-ray diffraction(XRD),transmission electron microscopy(TEM),selected area electron diffraction(SAED) and Vickers microhardness measurements(HV).The study was focused on the investigation of the precipitates formation and the relationship between hardness and lattice parameter for α-Al.The results showed that there was an inverse correlation for all the experimental conditions,and the aged peaks coincided with lattice parameter minima.Significant precipitates formation only occurred for the alloy containing 5.5 wt pct Zn and 2.1 wt pct Mg,provoking an important strengthening and variations in the lattice parameter,however,this was not observed for the alloy containing 2.2 wt pct Zn and 0.95 wt pct Mg.A plausible explanation of the increment of hardness values could be the presence of a well distributed η phase(MgZn2).At initial stages of the precipitation process,η was the most abundant precipitate while the phase τ was observed at overaged conditions.These results showed that the aging response of the conventionally cast Al-Zn-Mg alloys could be obtained using the lattice parameter of the α-Al matrix,even for alloy systems with low precipitates formation. | P.Fernandez G.Gonzalez I.Alfonso I.A.Figueroa | 2010 | Journal of Materials Science & Technology2010，26，12： | 0 |
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