Surface Oxides in P/M Aluminum Alloys

JOM - Aluminum powder particles inherently exhibit a surface oxide layer because of the reactivity of aluminum with oxygen. This surface layer detrimentally affects mechanical properties when...     

Al/SiCp复合材料的断裂行为

采用粉末冶金和喷射沉积方法制备了Al及Al／SiCp复合材料，测试了材料的力学性能，利用金相显微镜和扫描电镜观察了材料的断裂行为。结果表明，Al／SiCp复合材料的强度比基体材料的高，但塑性低。粉末冶金方法制备的Al／SiCp复合材料与喷射沉积方法制备的比较，前者组织更致密，强度更高，塑性更好，断裂是SiC颗粒开裂，裂纹的传递主要沿颗粒中形成的裂纹扩展；后者断裂主要表现为SiC颗粒从基体中拔出，裂纹的传递大多是SiC颗粒周围形成的裂纹在基体中扩展。     

PS版基冷轧成品道次产生粘铝的原因及应对措施

PS版基冷轧成品道次易产生粘铝，严重影响了版基表面质量，增加了PS版基生产成本，分析了PS版基粘铝的原因及应对措施。     

TA2表面电火花沉积Zr/WC复合涂层特性及界面行为研究

目的通过在TA2表面进行电火花沉积改变其表面性能。方法采用电火花沉积技术,在基体TA2表面制备Zr/WC复合涂层,然后分别用扫描电镜(SEM)、能谱分析仪(EDX)、X射线应力分析仪、显微硬度计和摩擦磨损试验机分析涂层的微观组织、化学成分分布、残余应力、显微硬度分布以及涂层的耐磨性。结果复合涂层连续、均匀,厚度约为50~80μm;涂层表面不平整,存在很多小坑和粘连,涂层内部有少量气孔和裂纹;复合涂层与基体的主要元素Ti、Zr、W之间发生相互扩散,并发生冶金反应;经过电火花沉积后TA2表面存在较大的残余应力,通过改变工艺参数可有效控制残余应力;复合涂层表面显微硬度值最高能达到960.5HV200g,约为基体的4倍;经过电火花沉积Zr/WC复合涂层的试样磨损量远远小于TA2试样,ε_w=4.1,沉积层的耐磨性比基体材料提高了3.1倍,经电火花沉积制备复合涂层后表面的耐磨性显著提高。结论在TA2表面电火花沉积Zr/WC复合涂层可以改善其表面性能。     

不锈钢/铝复合板的成形性能研究

通过拉伸试验和杯突试验对不锈钢,铝复合板成形性能进行了研究。试验结果表明：不锈钢层的应力状态决定了该复合板的成形性能,在拉伸和冲压变形过程中,裂纹首先都从不锈钢层开始,而且当不锈钢层在冲杯内侧（S．I）比起铝层在冲杯内侧（A．I）的复合板有更高的冲压变形能力。     

2A12铝合金0.3mm薄板的冷轧制工艺技术

2A12铝合金的变形抗力较大，冷轧薄板的成品率较低。对该合金薄板的冷轧工艺过程进行了分析，制定合理的冷轧工艺方案及其参数，提高了产品的成品率。     

Hf和Zr含量对FGH96合金平衡相及PPB的影响

采用材料热力学计算软件Thermo-calc,计算了FGH96合金中的平衡相,并结合显微组织观察、能谱和相分析,探讨Hf、Zr含量对γ’相和碳化物的影响,及对消除PPB的作用。结果表明:Hf和Zr不会导致产生新相,主要影响MC和γ’相的析出行为与成分。Hf和Zr能显著改变MC型碳化物的组分,增加其热力学稳定性和数量,促进MC型碳化物在合金中的均匀分布,抑制MC向M23C6转变;Hf还可以参与形成γ’相,增加其数量。Hf、Zr有助于消除FGH96合金中的原始颗粒边界(PPB)。     

腐蚀损伤铝合金表面超声焊接截面组织结构分析

在腐蚀受损的2A12CZ基体上采用超声焊接铝合金箔材的工艺进行了修复处理,并利用光学显微镜观察和分析了焊接时间对箔材与基体之间焊接界面组织的影响。结果表明:当焊接时间为0.6s时,箔材与基体之间呈断续的结合状态,能分辨出结合界面,且界面呈锯齿状或涡流状分布;当焊接时间为1.2s时,箔材与基体之间完全结合成一体,界面消失,呈冶金结合状态。最后对铝合金箔材与铝合金基体之间超声焊接机理进行了探讨。     

Ti—2Al—2.5Zr合金管,板材织构研究

利用Ｘ射线衍射极图测量技术,研究了Ｔｉ－２Ａｌ－２．５Ｚｒ合金轧制、拉拔管材的退火织构,并与轧制板材的织构进行了对比分析,结果表明：轧制管材环向主织构由棱锥织构｛１０１５｝和基面积构（０００１）等组成：而轴向主织构则包括棱柱织构｛１０１０｝和｛１１２０｝等棱锥织构;拉拔管材退只构类型与轧制管材相似,但其主织构盛会中度与轧制管材相比则发生较大变化;冷轧板材的退火织构随温度升高而发生转变。     

In-situ P/M Al/(ZrB2+Al2O3) MMCs: processing, microstructure and mechanical characterization

In-situ metal matrix composites (MMCs) offer significant advantages over conventional MMCs from both a technical and an economic standpoint. In this paper, an in-situ MMC, i.e. Al/(10 vol.% ZrB₂+9.2 vol.% Al₂O₃), is produced starting from Al+ZrO₂+B by reactive sintering and subsequently densified by hot-pressing. The formation mechanism of ZrB₂ and Al₂O₃ in Al matrix is studied by XRD, thermal analysis and microstructural characterization. Reaction kinetics are also investigated based on the results of the reaction mechanism. The properties are evaluated in terms of microstructural characterization, Young’s modulus and bending tests. The in-situ processing involves four intermediate steps and the transitional phases are AlB₂, Zr(O, B)₂ and (Zr, Al)(B, O)₂. Regarding the reaction kinetics, conversion fraction vs time relationships have been established for the last three intermediate steps.     

Heat-resistant bulk nanostructured P/M aluminium

In this work, a simple route to produce bulk nanostructured aluminium is presented. Firstly, a thermally stable nanocomposite Al powder is prepared by attrition milling of elemental Al in the presence of 2.1 wt.% urea. Then, the milled powder is consolidated to full density by a conventional press-and-sinter powder metallurgy (P/M) technique. Shaped specimens possess a stable microstructure, with a grain size of about 150 nm, and the ultimate tensile strength (550 MPa) surpasses that of most commercial Al alloys, especially at high temperatures.     

Optimization of Mechanical Properties of Hybrid Al2O3/SiCp Reinforced Composites Produced by Pressure-Assisted Aluminum Infiltration

This study investigates Al₂O₃/SiCp-Al composites fabricated by pressure-assisted liquid–metal infiltration techniques and modified alumina/SiC particle preforms. The infiltration was achieved successfully; microstructure and mechanical properties of the composites were examined. An experimental design based on the Taguchi technique was used to acquire the data and investigate the mechanical properties of the hybrid composites. An orthogonal array and analysis of variance were employed to investigate the influence of test parameters such as infiltration temperature and infiltration pressure. It was found that the infiltration temperature was the most effective factor in increasing the mechanical properties of hybrid Al₂O₃/SiCp composite.     

2A12—T81铝合金板材热处理工艺研究

研究了固溶热处理及人工时效工艺对２Ａ１２－Ｔ８１铝合金板材的组织与性能的影响规律,指出了适用于１００℃或更高温度下工作的板材的热处理工艺参数。     

P2缓蚀剂处理铝合金的耐腐蚀性能研究

目的：通过加入一种合成缓蚀剂提高锆化液防锈性能。方法将P2缓蚀剂磷酸三乙醇胺加入到锆化液中处理铝合金,使其表面形成一层新型锆化膜。用扫描电镜(SEM)分析处理后样品放大20000倍的表面,并与原液处理的样品进行对比,通过能谱(EDS)及XRD分析微团成分,辅助使用硫酸铜点滴试验判断耐腐蚀能力的增强程度,并用百格试验测试处理后表面对漆膜的附着力变化,通过酸性盐雾试验(CASS)分析新型锆化膜处理后的附着力变化程度。结果使用加入P2缓蚀剂的锆化液的辅助硫酸铜点滴实验,较原样颜色变化所用的时间提高了48 s,用加入缓蚀剂的锆化液处理的样品中,氧元素较原样品中氧元素减少了一半,判断微团为氧化微团且在加入缓蚀剂的锆化液处理后大量减少,百格实验效果相当,能通过480 h的CASS。结论使用添加P2缓蚀剂的锆化液处理铝合金,能增强其耐腐蚀性能。     

FGH97合金的显微组织

结合FGH97合金的制备工艺,采用显微组织观察等手段,对合金的显微组织进行了分析研究与讨论,结果表明,直接热等静压成形的FGH97合金的晶粒组织均匀,晶粒度为6～7级;合金中的Hf元素对减少合金中的原始颗粒边界(PPB)有着显著作用,同时,Hf元素会进入γ'相和碳化物,提高γ'相的强度和碳化物的稳定性;合金的显微组织具有弯晶特点,这对合金的塑性和韧性非常重要.