超高强铝合金研究进展与发展趋势

超高强铝合金具有密度低、比强度高等特点,广泛应用于航空、航天、核工业等领域。合金的极限强度已从第四代铝合金的600 MPa级,逐步发展到650~700 MPa级、750 MPa级,甚至800 MPa级及以上第五代铝合金。本文首先对超高强铝合金的发展历程和国内外发展现状进行概述;随后,从成分设计与优化、熔铸与均匀化技术、热变形技术、热处理技术、计算机辅助模拟计算共五个方面对近些年的研究进展和所遇到的问题进行了总结和讨论;最后,结合未来装备的发展需求和国内的技术现状,指出“深入研究基础理论,解决综合性能匹配等问题以及在特定应用场景下专用材料的推广应用”是超高强铝合金的发展趋势和重要方向。

从铅锌废渣中氨浸锌试验研究

研究了采用氨浸法从铅锌废渣中回收锌,以及用溶剂蒸发法制备碱式碳酸锌,考察了浸出温度、浸出时间、总氨浓度和液固体积质量比对锌浸出率的影响。结果表明:影响锌浸出率的因素排序为液固体积质量比>浸出时间>浸出温度>总氨浓度;在浸出温度30℃、浸出时间2h、总氨浓度4mol/L、液固体积质量比7mL/g适宜条件下,锌浸出率为81.99%;所制备的碱式碳酸锌为无定形状态,化学式为Zn5(CO3)2(OH)6·2H2O。

Microstructure and mechanical properties of forged Al-7.1Zn-1.1Mg-1.6Cu-0.14Zr alloy after two-step ageing treatment at 120 and 170℃

The tensile properties, electrical conductivity, and microstructure of the forged A1-7.1Zn-1.1Mg-1.6Cu-0.14Zr alloy were investigated after a two-step ageing treatment at 120 and 170℃. The results indicate that the strength of the alloy reaches the peak value at 170~C for 1 h during the second step ageing and then decreases sharply. However, the electrical conductivity value increases continuously with the second ageing time increasing. The fracture mechanism of the alloy is intergranular fracture for 1 h and then changes to dimple transgranular fracture later, and the toughness of the alloy is improved significantly. The phases of rl＇ and 1＂1 are major precipitates in the alloy under the two-step ageing condition. Discontinuous grain boundary precipitates and precipitate-flee zones along the grain boundary are clearly observed.

Effects of trace Zr on the microstructure and properties of 2E12 alloy

Al-4.0Cu-1.4Mg-0.6Mn （2E12） and Al-4.0Cu-1.4Mg-0.6Mn-0.3Zr aluminum billets were manufactured by soft-contact electromagnetic continuous casting （EMC）. Subsequent forging and heat treatment were conducted and the effects of Zr on the microstructure and properties of the Al-4.0Cu-1.4Mg-0.6Mn alloy were studied. The results show that the addition of 0.3% Zr can reduce the dendrite and refine grains. During forging and solution treatment, fine and dispersive Al3Zr particles precipitated from the supersaturated α （Al） solid solution in the heating process of the billet can effectively pin dislocations and subgrain boundaries. Because of the addition of Zr, the mechanical properties are improved with the tensile strength, yield strength, elongation, and contraction of the area increasing by 5.4%, 11.3%, 9.7%, and 12.6%, respectively. Moreover, under the condition of R = 0.1, the fatigue crack growth rate （da/dN） of the Al-4.0Cu-1.4Mg-0.6Mn-0.3Zr alloy is lower than that of the Al-4.0Cu-1.4Mg-0.6Mn alloy.

新型Al-Zn-Mg-Sc-Er-Zr合金的热变形行为

采用Gleeble-3800热模拟机研究Al-8.9Zn-1.3Mg-0.1Sc-0.1Er-0.1Zr铝合金的热变形行为,构建温度380~440℃、应变速率0.01~10 s^(-1)区间内合金的热加工图,使用X射线衍射(XRD)、选区电子衍射(SAED)与能谱(EDS)对合金中存在的物相进行分析,并使用金相显微镜(OM)和透射电子显微镜(TEM)观察合金热变形后的微观组织。结果表明:合金的最佳热加工工艺参数区间为:400℃<T<440℃,0.01 s^(-1)<ε<0.1 s^(-1)。变形后合金的主要相组成为α-Al和Al_(3)(Sc,Er);塑性变形所需的应力随温度的升高和应变速率的降低而减小,主要是由于再结晶的发生和Al_(3)(Sc,Er)粒子钉扎力的减小;低应变速率下,发生动态软化的倾向更大,软化机制由动态回复转变为动态再结晶;绝热剪切带与位错塞积的形成是导致合金失稳的主要原因。

利用铅锌废渣制备银修饰纳米复合材料的研究

以含银的铅锌废渣为银源,联合采用氯盐法、Stober法、溶胶凝胶法以及光沉积法制备银修饰纳米复合材料Ag@TiO_2@SiO_2。XRD和TEM的分析表明:Ag@TiO_2@SiO_2具有核壳结构的纳米材料,Ag以10nm团簇的形式沉积在锐钛矿型TiO_2壳层上。XPS分析指出:TiO_2以Ti-O-Si键化学吸附在SiO_2上,而沉积在TiO_2上的银是银的单质。Uv-Vis的分析表明:材料Ag@TiO_2@SiO_2对光响应范围扩大到可见光区。罗丹明的光降解反应表明,Ag@TiO_2@SiO_2的光催化性能优良。

铝合金砂型低压铸造界面传热系数的测定

以典型板形试样的砂型低压铸造为基础,采用热传导反算法对ZL114A铝合金/树脂砂的界面传热系数进行了反求,并对界面传热系数随温度的变化关系进行了分析。结果表明,界面传热系数在液相线温度以上时基本保持恒定,约为335W獉m^(-2)獉K^(-1);当温度下降到530～573℃之间时,界面传热系数迅速下降;当温度下降到530℃之后,界面传热系数缓慢下降,最后逐渐稳定在60W獉m^(-2)獉K^(-1)左右。通过对反求得到的界面传热系数进行非线性拟合,得出了该工艺条件下界面传热系数随界面温度变化的经验公式。最后将反求得到的界面传热系数应用到ProCAST软件中对铸件的温度场进行仿真计算,计算结果表明,模拟温度与实测温度具有较好的一致性,最大温度偏差约为12℃。