B-Ni、B-Fe系离子束混合实验研究

近年来,常用离子束混合法来研究二元金属系统的合金化问题。但是,在用离子束混合法研究类金属-金属二元系统结构变化方面,除掉Si与Pt、Pd等金属的单层膜反冲混合外,迄今还未见有研究资料发表。然而,类金属元素在金属的离子束表面改性中,以及在用其它方法形成非晶态等的研究中,是常用的元素。因此,研究类金属-金属在离子束作用下的结构变化具有现实意义。     

用~(16)O(α,α)~(16)O共振散射研究氧杂质对WSi_2形成及其性质的影响

用~(16)O(α,α)~(15)O共振散射在E_R=3.042MeV共振,分析样品中氧含量及浓度分布,研究了离子束混合引起的W-Si多层薄膜间的反应及形成的WSi_2薄膜性质与膜中氧杂质浓度的关系,氧的再分布与退火温度的关系。发现随着退火温度升高,氧朝表面扩散。形成硅化物时氧从硅化物中排出,并在表面和硅化物与单晶硅衬界面积累。在350℃下用As离子辐照时,含氧较低的样品直接形成六角WSi_2相,含氧较高的样品没有得到六角WSi_2相。含氧较少的样品,在离子束辐照下混合较均匀,形成的二硅化钨薄膜有较大的晶粒和较小的电阻。     

离子束混合对铝合金腐蚀行为影响的阳极极化研究

用离子束一次混合、二次混合和氧化处理在LY11硬铝合金基体上形成防护层。在3％NaCl溶液中采用三电极动电位扫描法测定各试样的一次阳极极化和环形极化曲线,比较其自然腐蚀电位、点蚀击穿电位、保护电位、可能点蚀区宽度以及极化电流等电化学参数。发现离子束二次混合形成的富Cr新合金层远优于一次混合或氧化处理的防护层。用RBS分析获得混层合金元素的纵向分布,证明在二次混合情况下,Cr与基体产生了良好的混合。     

H+辐照对不锈钢基体上涂覆W膜的微观研究

对奥氏体不锈钢基体上采用离子束混合技术进行不同厚度的钨膜沉积，沉积后的试样进行了H^ 注入前后的XRD和SEM微观分析，研究了H^ 辐照对W膜的晶体结构和形象的影响。结果表明，沉积的W膜基本上是非晶的，还出现了由于污染造成的钨的氧化物。氢离子的辐照模拟结果表明，少量晶化的W向非晶化转变，污染的氧化物被择优溅射掉。H^ 轰击对W膜表面形貌的影响不大，它仍然致密、均匀、完整且无明显损伤。     

动态离子束混合技术制备氧化铬薄膜的X射线光电子能谱与俄歇电子能谱研究

本文介绍的动态离子束混合技术制备氧化铬薄膜系在不锈钢基体上进行1keV氩离子束溅射沉积铬(同时通入一定量的O),并用100 keV的氩离子束或氧离子束轰击该样品.对两种离子束轰击形成的氧化铬薄膜进行了X射线光电子能谱(X-ray photoelectron spectroscopy,XPS)和俄歇电子能谱(Auger electron spectroscopy,AES)的分析研究.发现Ar 离子束制备的氧化铬薄膜主要是Cr2O3化合物,而O 离子束制备的氧化铬薄膜含有其它价态的铬氧化物.Ar 离子束制备氧化铬薄膜的污染碳少于O 离子束制备.与O 离子束制备相比较,相同能量的Ar 离子束轰击更有利于提高沉积的Cr原子与周围O2的反应性;Ar 离子束制备的氧化铬薄膜过渡层的厚1/3左右,较厚的过渡层显示了制备的薄膜具有较好的附着力.     

离子束混合形成氮化钛膜的摩擦和光学性能

用载能氮离子束轰击纯铁镀钛膜样品，成功地形成了金黄色氮化钛薄膜。结果表明：注入剂量为０．５×１０＾１７ Ｎ＾＋／ｃｍ＾２的混合样品表面颜色与纯金类似；氮离子束混合样品表面显微硬度及耐磨性都远优于纯铁基体，且随离子剂量的增加，混合样品的表面硬度和耐磨性也提高。     

离子束混合-材料表面改性

离子束穿过薄标记层要引起层内物质浓度沿深度分布的弥散。同样,离子束穿过金属和半导体或金属和金属之间的交界面,也要引起这种弥散。用真空沉积法,在SiO_2那样不活泼材料表面上沉积二个或多个元素薄层,以形成多层结构的样品。然后,在一定的温度下用Ar~ 、Kr~ 或Xe~ 那样的惰性气体离子束流轰击,可形成各种平衡的和亚稳定的化合物,无定形层或固溶体,这就是离子束混合(Ion-Beam Mixing)。     

Ar离子束致非晶Ti-Al和Fe-Al合金的形成

本文对室温下100keV Ar离子束注入到Ti-Al和Fe-Al两个二元系中几种成分的样品进行了研究。透射电镜、背散射分析和表面电阻测量被用于对多层膜离子束混合过程的分析。研究结果表明:Ti-Al二元系中能在很宽的成分范围内形成非晶相,而Fe-Al二元系中只有成分为Fe_(25)Al_(75)附近的样品中才观察到非晶相的形成。对这两个系统中的结果,本文进行了初步的讨论。     

强脉冲离子束辐照混合的RBS研究

采用卢瑟福背散射(Rutherford backscattering spectroscopy,RBS)方法对强脉冲离子束辐照Ti/Al、Al/Ti和Ni/Ti三组薄膜/衬底体系所形成的混合层进行了研究.在Ni/Ti组合中形成了厚度比离子射程大得多的、混合度较高的梯度混合层.发现熔融态混合的程度不仅取决于两材料在熔融态的表面张力的差别,而且取决于它们熔点的差异.这两个参量较接近的混合程度较好.     

强脉冲离子束辐照混合陶瓷/NiCoCrAlY热障涂层研究

为提高高温合金的工作温度,一般在其表面涂覆由粘结过渡层和陶瓷隔热层构成的热障层.热障层的热稳定性决定了高温合金部件的寿命.为延长由部分稳定的ZrO2/NiCoCrAIY合金构成的热障层的服役寿命,采用强脉冲离子束对它们的界面进行辐照处理.本工作研究了不同参数的强脉冲离子束(IPIB)对不同厚度结构的靶的辐照混合效应,通过一系列分析测试研究,发现合适参数的IPIB辐照能够有效地在界面形成混合层,从而改善热障层在高温氧化环境中的高温耐久性.其中采用峰值能量300 keV,脉冲宽度65 ns,峰值流强密度250 A/cm2的IPIB单脉冲辐照后的样品获得最好效果.对其原因做了分析,认为在界面处形成特定元素分布的混合层在高温氧化条件下既能形成完整的保护层,又改善了层间晶格和热胀系数失配,减小了失配热应力,从而提高了热障层在高温氧化条件下的稳定性.     

COMPETING REACTIONS OF EXISTING Ni SILICIDE AND Ni OR Si INDUCED BY THERMAL ANNEALING AND MeV Si ION BEAM MIXING

The competing reactions between existing Ni silicides surrounded by Si and Ni were investigated by thermal annealing and MeV Si ion beam mixing. With high energy irradiation, the energy deposition at both interfaces, Ni/Ni silicide and Ni silicide/Si, is equal. Two MeV He~- RBS and TEM were used to obtain the reacted layer composition and epitaxial orientation, respectively. Also glancing angle Co K_a. X-ray diffraction was utilized to identify phase formation. The main results indicate that the existing silicides preferentially react with Ni layer, and that there are pronounced differences of Ni silicide phase transition between thermal annealing and MeV Si ion beam mixing, even though the mixing was performed in radiation enhanced diffusion regime. The results can be explained in term of the heat of silicide formation and surface energy change.     

As离子注入形成硅化钨的研究

大规模集成电路的发展使集成度不断提高,器件尺寸减小,线条变窄。现常用的多晶硅栅和互连,由于电阻率高,限制了集成电路的速度。近年发展起来的硅化物材料,因其电阻率低、稳定性好、自对准性能好而常被用作大规模集成电路中的欧姆接触,互连和肖特基势垒。     

Ni/Si体系离子束混合及相变研究

注入参量变化引起不同的混合结果,在宽温区中得到Ni_2Si、NiSi、NiSi_2多种化合物相,进而探讨了Xe离子诱导的Ni/Si体系界面原子混合机理及诱发相变的动力学过程。     

Search for implantation-induced “re-solution” of Na precipitates in MgO via optical spectroscopy and in situ TEM

It has previously been shown that high fluence Na implantation into MgO crystals followed by annealing leads to the formation of metallic Na precipitates. We have studied the effect of a subsequent low-fluence Na implantation on such precipitates, i.e., the effect of Na damage cascades whose size is comparable to that of the precipitates. Optical spectroscopy experiments and in situ transmission electron microscopy (TEM) experiments performed on-line with the Orsay ion implantor are both discussed. It is shown that simple ballistic ion beam mixing cannot account for the results. The latter indicate that damage-induced mixing at the host matrix-precipitate interface leads to drastic changes in the precipitate composition, presumably due to in-diffusion of oxygen (and possibly Mg) into the precipitate volume.     

Atomic mixing in thin film systems by swift heavy ions

Because of their sensitivity to the electronic energy loss of swift heavy ions, we have investigated the high energy ion beam mixing of oxide layer systems. In this paper we present a summary of the results and first steps towards interpretation and modelling of the observed phenomena. As was also observed in the case of track formation, mixing was found to occur only if the electronic energy loss exceeds a threshold value. The threshold is determined by the less sensitive material, which is a clear hint that both sides of the interface must have been molten, to enable for effective interdiffusion. This interpretation is supported by the estimated interdiffusion constants which indeed lie in the range known for liquid state diffusion.     

Single Particle and Collective Effects Observed in the Electron Beam of the Maryland ERA Experiment

The formation of rotating, relativistic electron beams with properties suitable for collective ion acceleration has been studied under a variety of experimental conditions. A straight, cylindrical, relativistic electron beam (typical energy 2-3 MeV, typical current 2-10 kA) is passed through a narrow magnetic cusp, and the resulting rotating downstream beam has been studied using a number of diagnostic techniques. Two current regimes have been investigated: one in which the self-fields of the downstream electron beam are small compared to the applied fields, and one in which the self-fields are comparable to the applied fields. The beam characteristics in both regimes have been compared to single particle expectations. Experiments have also been conducted in which the effect of an inner and outer conducting boundary on the time-resolved beam cross section has been measured. Results will be discussed in the context of collective ion acceleration experiments now in preparation.     

Mechanisms in the ion beam mixing of Al in Si

Ion beam mixing of Al in Si has been studied by implanting 100 keV ⁴⁰Ar⁺ ions into 300 Å Al overlayers on Si substrates. The mixing of the collisionally similar Al and Si atoms was studied with the nuclear resonance broadening technique. It is characterized to be proportional to the square root of ion fluence. The mixing is compared with that of Al in Si due to irradiation with 40 keV ²²Ne⁺ ions studied recently by us. Mechanisms which enhance the observed atomic mixings with about 5 times that expected for ballistic mixing have been studied by Monte Carlo simulation of the collisional cascades. The results indicate the need to revise the present model of the ballistic mixing by focusing more attention to the effect of low-energy impurity—matrix atom collisions.     

低温离子束混合形成非晶态Pd_(0.67)B_(0.33)合金

Stritzker和Becker用离于注入法制备了PdB_(1.5)合金,证实它具有超导性。Orsay组曾系统地研究过离子注入Pd_(1-x)B_x系(0≤x≤0.54)的电学性质,表明当B的浓度达到共晶浓度(x=0.27)时,Pd_(1-x)B_x为非晶态;当B的浓度x≥0.40时,样品具有超导性。 离子束混合利用载能离子穿越不同元素薄层和固体原子碰撞,引起原子离位的输运作用,