高Mg含量Al-Mg-Sc-Zr合金选区激光熔化成形性及力学性能

基于宽粒径分布粉末(2～46 μm),应用选区激光熔化(SLM)技术制备了高Mg含量Al-14.4Mg-0.33Sc-0.19Zr铝合金.系统研究了不同工艺参数和时效处理条件对合金SLM 成形性、组织和力学性能的影响.结果表明,高激光功率可有效降低细粉飞溅对样品成形性的干扰,SLM 成形样品的最大相对密度为98.6％....     

激光功率密度对SLM成形TC4磨损性能的影响

采用激光选区熔化技术(selective laser melting, SLM)制备TC4磨损试样,探究不同激光功率密度对SLM试样磨损性能的影响. 采用MMW-1A万能摩擦磨损试验机测试不同功率密度下SLM试样的耐磨损性能,通过X射线衍射仪(XRD),X射线能谱仪(EDS)和扫描型电子显微镜(SEM)表征SLM试样的成分和结构,并用显微硬度仪测试硬度. 结果表明,SLM试样比精铸TC4磨损过程更稳定,提高激光功率密度有利于激光细晶强化作用,提高了材料的抗磨损性能.     

选区激光熔化制备AlCoCrFeNi高熵合金的成形性能

采用选区激光熔化(SLM)技术制备了AlCoCrFeNi高熵合金,研究了激光工艺参数对成形性、致密度、微观组织以及力学性能的影响。结果表明,随体能量密度的增加,致密度逐渐增加,最佳的SLM参数为激光功率50 W,扫描速度300 mm/s,扫描间距70 μm,层厚30 μm。铸态和SLM态合金是由无序BCC相(A2)和有序BCC相(B2)组成的双相体心立方结构,由于细晶强化作用,选区激光熔化试样具有比铸态试样更高的显微硬度,但是压缩屈服强度降低,原因是选区激光熔化合金中存在裂纹、孔洞等缺陷。     

选区激光熔化法制备的M2052锰铜合金的组织与性能

使用真空感应熔炼气雾化法(VIGA)制备M2052锰铜粉末,通过选区激光熔化技术(SLM)直接成形合金试样,经固溶时效处理和热等静压加工,从热力学计算、显微组织分析及力学性能测试等方面对SLM法制备的锰铜合金进行了研究。研究发现SLM法成形的锰铜合金的抗拉和屈服强度较高,但冲击吸收能量低,塑性差。经过热等静压处理后,合金的综合力学性能明显提高。     

激光增材制造设备现状及发展

激光增材制造技术主要包括粉末床熔融(PBF)和定向能量沉积(DED),粉末床熔融指的是激光选区熔化(SLM),定向能量沉积指的是激光近净成形(LENS).伴随着这些技术"诞生"了相应的激光增材制造设备.以华南理工大学相应设备研发为例,介绍了相关技术设备现状,并展望了激光增材制造设备未来的发展.     

激光选区烧结陶瓷粉末材料的研究进展

根据国内外对激光选区烧结使用陶瓷粉末材料的研究成果,分别介绍了四类陶瓷粉末材料的研究现状,并分析了粘结剂直接混合,表面覆膜、表面改性等在陶瓷粉末材料激光烧结机制中的影响,结合陶瓷粉末材料在激光选区烧结应用中存在的问题,讨论了进一步研究陶瓷粉末材料的发展方向.     

VIGA法制备的M2052锰铜合金粉末及其SLM打印件的性能

采用真空感应熔炼气雾化法(VIGA)制备了M2052锰铜合金粉末,分析了M2052锰铜粉末的物性和显微组织;用选区激光熔化3D打印技术(SLM)制备锰铜试样,并分析热处理前后SLM成型的锰铜合金的组织与性能。结果表明,VIGA法能够有效地控制金属粉末形状,制备的15~53 μm粒度区间的锰铜粉末收得率高,松装密度高,具有较好的球形度,有效满足SLM用金属粉末的要求。由SLM制备的锰铜打印件横纵向具有不同的微观组织,随熔池内部延伸逐渐变为胞状晶,沿焊接界面形成柱状晶,离熔池越远柱状晶越细。与铸态合金相比,SLM方法制备的锰铜合金具有明显的力学性能差异,SLM打印件的抗拉强度为611 MPa,规定塑性延伸强度为504 MPa,远远高于铸态母合金的454 MPa和172 MPa。其原因是打印件细晶强化效果明显,但微裂纹的存在对塑性不利。     

齿科用钛合金粉末粒度对激光选区熔化工艺适用性研究

激光选区熔化(SLM)是一种在医疗领域应用越来越广泛的3D打印工艺,用SLM技术打印齿科钛合金粉末,可以制作出个性化且具有复杂结构的口腔医疗器械。为了研究粉末粒度对SLM工艺的成形适用性,本研究选择了齿科用Ti-6Al-4V合金粉末作为成形材料,通过不同目数的筛网对粉末进行分级,得到不同粒度范围的钛合金粉末。采用EOS M280设备分别成形不同粒度范围的粉末,并对成形过程和成形件表面质量进行对比分析,得出当粉末粒度范围为15~53μm时,熔道连续无缺陷,成形件表面光滑平整,有金属光泽。该粒度范围粉末成形件的内部孔洞很少,强度和塑性均优于铸造件。粒度范围为15~53μm的齿科用钛合金粉末适用于激光选区熔化工艺。     

铁单元素基合金表面激光高熵合金化涂层的制备

利用高功率半导体激光器进行合金化处理,采用等摩尔比的Co,Cr,Al,Cu四主元合金粉末,在Fe单元素基合金Q235钢表面成功制备出FeCoCrAlCu激光高熵合金化涂层.利用SEM,XRD,EDS及显微硬度计对FeCoCrAlCu激光高熵合金化层的微观组织形貌、相结构、成分分布及性能进行系统研究.结果表明:Q235基材主元素Fe在激光辐照时参与了表面合金化过程,形成了FeCoCrAlCu五主元高熵合金涂层;合金化层相组成为具有简单bcc结构的固溶体,显微组织为典型的枝晶组织;激光高熵合金化层仅在基体界面附近出现了少量s四方结构中间相,从高熵合金化层表面到基材,体系的混合熵呈高熵-中熵-低熵梯度变化;FeCoCrAlCu激光高熵合金化涂层的显微硬度高达8.3 GPa,为基材Q253钢的3倍以上.     

Al-Mg-Li合金选区激光熔化成形及热处理工艺

设计并制备了多种不同成分的铝锂合金粉末，对其进行了选区激光熔化(SLM)成形，选取高致密、无裂纹的自研铝镁锂合金成形零件进行了热处理工艺研究。结果表明，第三代Al-Li-Cu系铝锂合金在选区激光熔化成形快速凝固过程中极易产生微裂纹，第二代Al-Li-Mg系合金较为适合选区激光熔化成形，能够得到高致密、无裂纹的成形样件；选区激光熔化成形铝镁锂合金在200℃进行时效热处理，强化相主要为δ′相，时效48 h达到峰时效状态，继续延长时效时间，其力学性能有所下降。     

Phase diagram sample preparation

The procedures by which samples are prepared for phase diagram studies are examined and critically evaluated. The three key elements that require attention (alloy purity, homogeneity, and equilibrium) are separately addressed, and several examples of bad procedure are presented with information on their past and future consequences. The origin of commonly confronted problems are described and special procedures are suggested for their circumvention. Additionally, new methods for the early detection of some sample problems are presented, and the usefulness of rapidly solidified materials (as specimens) in phase diagram studies is illustrated.     

制备P型沸石工艺的研究

本文介绍了制备P型沸石实验原理,以及利用含硅酸钠的铝酸钠溶液通过机械化学法制备P型沸石试验研究.P型沸石的制备方法采用了机械化学法制备,工艺简单,可直接一步制得P型沸石.     

Electrochemical preparation of chiral polyaniline nanocomposites

Optically active polyaniline colloids have been generated in high yield via the electrohydrodynamic polymerisation of aniline in the presence of 1.0 mol dm⁻³ (+)- or (−)-camphorsulfonic acid as dopant using colloidal silica (5% w/w) as dispersant and an applied potential of +0.8 V (vs. Ag/AgCl). Both the rate of polymer formation and the degree of chiral induction in the polyaniline chains were enhanced compared to colloid formation using polystyrenesulfonate (PSS) as steric stabiliser. Higher chiral induction was achieved using 10% w/w silica as dispersant, while lower silica concentrations (e.g., 2.5% w/w) led to over-oxidation. Lower (+)-HCSA concentrations (≤0.5 mol dm⁻³) also caused over-oxidation. The dispersions using 5 and 10% w/w silica were very stable, showing unchanged chiroptical properties after 3–4 months. The particle size (300–600 nm) increased with increasing polymerisation time. Transmission electron micrographs (TEM) studies on the dried PAn.(+)-HCSA/silica colloid also showed large (200–600 nm diameter) particles, which on high magnification were seen to be nanocomposites consisting of individual polymer-coated silica particles (ca. 20 nm) fused together to give a raspberry-like morphology.     

电子背散射衍射的制样方法和影响花样质量的因素

概述了电子背散射衍射(EBSD)原理.EBSD试样的制备质量很大程度上决定着EBSD测试的可行性和花样的质量.介绍了各种抛光方法的优缺点,包括机械抛光、化学抛光、电解抛光和离子束处理等.总结了影响EBSD花样质量的因素,主要包括样品的状态、电镜参数的设置和数据获取软件参数的设置等.研究对于EBSD技术的初学者具有很好的...     

Surface preparation for the LDH test

The present work is aimed at developing a surface preparation technique that reduces or eliminates random variations often found in the limiting dome height (LDH) test without diminishing the ability of the test to discriminate between different batches of material. Degreasing with a nonpolar solvent (mineral spirits) followed by the application of a low viscosity mineral oil (mineral seal oil) gave the best results and was adopted as a standard. With this preparation, the LDH was as low as with sheets degreased with chlorinated solvents, while scatter was reduced. Surfaces prepared by wiping with a clean towel gave higher LDH values, corresponding to a surface coated with SAE 30 oil. None of the preparation methods could completely eliminate or mask residual films left by oils compounded with boundary or EP additives. Day-to-day variations were evident with all preparation techniques employed over a period of three months. However, when all LDH means were plotted as a function of sheet location in the coil, the means defined a curve which—within the limited coil length represented by the total sample quantity available—had a period of about 15 m (45 ft). Thus, random variations observed in the laboratory and press shop can be attributed to small variations in mechanical properties, revealed by the great sensitivity of the LDH test and not necessarily detectable by tensile tests. Surface preparation may contribute to random variations but such contribution can be eliminated by the standard preparation technique.     

非晶态合金制备方法

对现有的制备非晶的各种方法进行了综述,重点介绍了大块非晶的制备方法,介绍并分析了大块非晶合金成分的选择原则,对非晶制备方法进行了明确的分类,并对它们的优缺点进行了讨论和初步的对比。提出了非晶制备领域存在的问题及发展方向。     

Laser surface preparation of vitrified grinding wheels

A new method for surface cleaning loaded grinding wheels is introduced by applying CO₂ laser irradiation onto the grinding wheel surface. It was demonstrated that effective cleaning can be achieved by selection of the laser power flux and the duration of the irradiation. Fusion and evaporation of clogged metal chips play important roles in the laser cleaning process. It is suggested that high laser power irradiance and short irradiation duration are essential for effective grinding wheel cleaning. This paper was presented at the fourth International Surface Engineering Congress and Exposition held August 1–3, 2005 in St. Paul, MN.     

浅谈制备ASME无损检测演示试板

ASME特别强调NDEI艺规程的量化要求和演示验证要求,获取ASME认证的企业,在取证和换证及NDEI艺规程中重要变素变更时,都需要NDEⅢ级人员进行现场演示,并得到AI的认可。成功制作带有缺陷的演示试板,对NDEI艺规程的有效评定和验证,具有重要意义。本文是对取证中制备演示试板的总结,仅供广大同行交流和参考。     

半固态金属浆料制备新技术

半固态加工技术具有许多优良的特点，近年来得到迅速发展。广泛用于生产半固态金属的方法为触变成形，而流变成形与触变成形相比，前者更节约能源、流程更短、设备更简单，因此流变成形技术将是金属半固态加工技术的发展方向。半固态加工技术的发展趋势是，进一步简化加工工艺流程，进一步降低加工成本，扩宽半固态加工技术的应用范围。本文主要介绍最近几年在半固态浆料制备和加工中的几种新工艺和新技术的原理、特点及其应用，其中有新MIT工艺、冷却斜槽法、双螺旋流变注射成形法、剪切一冷却一轧制法、NRC工艺、不同液体混合法、近液相线铸造法等方法。