基于数字图像处理的钨合金塑性变形分析

分析了钨合金在不同温度下拉伸断裂后的显微组织。基于数字图像处理的方法分析了钨合金塑性变形与显微组织的关系。结果表明:运用数字图像处理法可准确得出钨合金显微组织的塑性变形量,其变形量和钨合金宏观塑性变形曲线基本保持一致。     

亚共晶Al-Si合金显微组织特征参数与电导率的本构关系

利用显微组织拓扑转换方法,建立了亚共晶Al-Si合金显微组织特征参数和其电导率之间的本构方程,可以综合考察变质处理和细化处理的效果。细化处理和变质处理之所以提高亚共晶Al-Si合金的电导率,是因为改善了亚共晶Al-Si合金显微组织特征参数。     

高铝锌合金的铸态组织和机械性能关系分析

本文通过对比分析新研制的高塑韧性高强度锌合金和ZA27合金的显微组织,观察和分析了试样断口处显微组织的变化,研究了锌合金机械性能和显微组织间的关系,探讨了新研制合金塑韧性好的组织原因。     

Al-P中间合金细化变质过共晶铝硅合金显微组织研究

在过共晶Al-22%Si合金熔体中添加Al-P中间合金,采用光学显微镜观察分析Al-P中间合金对过共晶铝硅合金显微组织细化变质的效果。研究结果显示,未经Al-P中间合金细化变质的Al-22%Si合金显微组织粗大;添加Al-P中间合金的Al-22%Si合金显微组织发生了很大改善,粗大块状初晶硅的尺寸减少,转变为纤维状,针状共晶硅转变为短棒状甚至是颗粒状,获得了良好的细化变质效果。     

一种改型Inconel718合金的组织与性能的研究

采用化学相分析、显微组织分析和显微硬度测试等方法,研究了一种改型镍基高温合金718A在标准热处理状态的显微组织和力学性能。试验结果表明,原型718合金和改型718A合金的主要析出相皆为γ″、γ′、δ、MC相。在标准热处理状态下,改型718A合金中强化相γ′和γ″的量较原型718合金明显增多,而对于组织稳定性不利的8相的析出量则较718合金少。此外,改型718A合金的显微硬度与原型合金相比有了明显的提高,因此具有广阔的应用前景。     

Mg?RE挤压合金晶体学织构与力学性能各向异性分析

本论文研究了热挤压加工对Mg-1Gd-1Nd (wt.%)合金显微组织、织构及力学性能的影响。研究结果表明,铸态合金呈现典型的共晶显微组织,包含α-Mg基体及半连续状的共晶化合物。经过固溶热处理后,这些共晶化合物已基本固溶入α-Mg基体中。采用电子背散射衍射(EBSD)技术分析了挤压合金的显微组织与织构。结果表明,挤压合金显示出了完全再结晶的显微组织与弱的基面织构。合金中的晶粒基面同时朝向挤压板材的挤压方向与垂直方向偏移,尤其在挤压方向上晶粒的取向更加分散。这种分散的取向可以有效地激活合金中的基面滑移使得合金在断裂前能够承受更大的塑性变形。另一方面,织构也影响了合金力学性能的各向异性。     

Sc对Ti-Al二元合金组织与显微硬度的影响

采用真空电弧熔炼技术制备了Ti-6Al、Ti-3Al-35c、Ti-10Al以及Ti-8Al-2Sc四种成分的合金，借助X射线衍射技：术(XRD)对铸态合金的相组成进行了分析。将铸态合金分别在β相区、α＋β相区和仅相区的温度下进行真空等温退火10h并进行水冷。借助光学金相显微镜对合金在不同退火态下的组织进行了分析，并用岛津显微硬度计测量了合金的显微硬度。试验结果表明，铸态Ti-Al-(Se)合金的显微组织形貌主要为魏氏组织、双态组织和网篮组织，其主要析出相为Ti-Al和Al3Sc。金属sc的加入明显细化了合金的组织，同时提高了合金中α片层组织的显微硬度。从金属Sc对合金的组织演变的影响上来看，金属Sc的加入具有稳定仅相的作用。经过等温退火处理后的合金其显微硬度高于铸态合金的显微硬度，Al的含量以及金属Sc的添加均对合金基体和片层组织的硬度产生了一定的影响。     

调幅结构对Ni-Fe-Nb-Al合金物理参量的影响

研究了Ni-Fe-Nb-Al合金在不同热处理条件下显微组织的变化。指出合金磁性和其它物理参量的变化与显微组织密切相关。     

电磁模拟微重力+电脉冲复合场作用下Cu-20Pb亚偏晶合金的组织与性能

在常规和电磁模拟微重力+电脉冲复合场作用下分别制备Cu-20Pb亚偏晶合金,对合金的显微组织、显微硬度、耐磨性能进行分析。结果表明,Cu-20Pb亚偏晶合金由基体α-Cu和基体间的组织β-Pb组成,常规条件下制备的亚偏晶合金基体上存在偏析组织,枝晶较粗,晶粒尺寸大,组织均匀性差;复合场下的亚偏晶合金基体上的偏析组织得到抑制,枝晶变得细小致密,晶粒尺寸减小了70.1%,组织均匀性好。显微硬度测试表明,经复合场处理后Cu-20Pb亚偏晶合金显微硬度得到提高,平均显微硬度提高了29.68%。摩擦磨损试验表明,复合场下制备的Cu-20Pb亚偏晶合金拥有更低的摩擦因数和磨损量,合金的耐磨性能得到提高。     

EFFECT OF THE MODULATED STRUCTURE ON PHYSICAL PARAMETER OF A NiFeNbAl ALLOY

研究了Ni-Fe-Nb-Al合金在不同热处理条件下显微组织的变化。指出合金磁性和其它物理参量的变化与显微组织密切相关。     

Comparison of castability,mechanical, and corrosion properties of Mg-Zn-Y-Zr alloys containing LPSO and W phases

The Mg-Zn-Y-Zr alloys with long-period stacking-ordered (LPSO) and W eutectic phases were investigated to develop new magnesium casting alloys. The temperatures for T6 heat treatment were selected based on the hardness and electrical conductivity measurements. The hot tearing susceptibility of the alloys with LPSO phase is lower than that of the alloys with W phase, which is associated with the freezing range of the alloys. However, the investigated alloys displayed the same fluidity. Under T6 conditions, increasing the Y content in the alloys resulted in increased yield strength, whereas other tensile properties were similar for the alloys. The corrosion resistance was higher for the alloys with LPSO phase compared to that of the alloys with W phase. Mg-2.5Zn-3.7Y-0.3Zr (mass fraction, %) alloy with LPSO phase possessed high castability and mechanical properties, with a corrosion rate of 2 mm/year.     

粉末冶金Al-1．1Sc和Al-2SC合金晶体结构的实验和第一性原理研究

采用气体雾化合金颗粒制备Al-1．1％Sc和Al-2％Sc合金。采用x射线衍射分析合金样品以确定样品的晶格参数。利用这些晶格参数,分别通过WIEN2K和EMTO程序对该合金的力学性能进行理论计算。将实验得到的合金的弹性模量和理论计算结果进行比较。讨论了计算得到的A13Sc相和AI—Sc合金的力学性能以确定Al-Sc合金中最佳的Sc含量。结果表明,最高的Sc含量约为1．0％,更多的Sc不能提高合金的力学性能。     

ECAP对连铸Cu-Ag合金断口形态及力学性能的影响

采用连续铸造和等径角挤压变形(ECAP)加工集成技术制备Cu-Ag合金,研究其力学性能和相应的拉伸断口形态。研究发现,Cu-Ag合金的强度随着ECAP加工道次和Ag含量的增加而增加,而延伸率却下降。连续铸造和ECAP加工的合金与传统浇铸和ECAP加工的合金相比,缩颈前静态韧性有所提高。同时发现,只有连铸的Cu-Ag合金在断裂前表现出缩颈现象,而经ECAP挤压后试样的断裂变为剪切模式,随着ECAP道次的增加出现不同的剪切断裂角。基于实验结果,讨论了经ECAP挤压后连铸Cu-Ag合金的拉伸断裂机制。     

Wear and isothermal oxidation kinetics of nitrided TiAl based alloys

Gas nitridation of TiAl based alloys in an ammonia atmosphere was carried out.The evaluation of the surface wear resistance was performed to compare with those of the non-nitridd alloys.It is concluded that high temperature nitridation raised wear resistance of TiAl based alloys markedly.The tribological behaviors of the nitrided alloys were also discussed.The oxidation kinetics of the nitrided TiAl based alloys were investigated at 800-1000℃ in hot air.It is concluded that nitridation is detrimental to the oxidation resistance of TiAl based alloys under the present conditions.The nitrided alloys exhibit increased oxidizing rate with the prolongation of nitridation time at 800℃.However,alloys nitrided at 940℃ for 50h display a sign of better oxidation resistance than the other nitrided alloys at more severe oxidizing conditions.The parabolic rate law is considered as the basis of the data processing and interpretation of the mass gain vs time data.As a comparison with it ,attempts were made to fit the data with the power law.The oxidation kinetic parameter kn,kp and nwere measured and the trends were discussed.     

快淬工艺对La-Mg-Ni系贮氢合金微观结构及电化学性能的影响

用铸造及快淬工艺制备了La-Mg-Ni系（PuNi3型）贮氢合金La2Mg（Ni0．85Co0.15）9Bx（x=0，0．1，0．2），分析测试了铸态及快淬态合金的微观结构与电化学性能，研究了硼及快淬工艺对合金微观结构及电化学性能的影响。结果表明，铸态合金具有多相结构，主相包括（La，Mg）Ni3相（PuNi3型）和LaNi5相，残余相为一定量的LaNi2相和微量的Ni2B相，经快淬处理后Ni2B相消失，并且其它相的相对量随淬速的变化而变化。不含硼合金的容量随淬速的增加而单调减小，含硼合金的容量随淬速变化有一个极大值。合金的循环寿命随淬速的增加而增加，铸态及快淬态合金均有优良的活化性能。     

A356合金的低周疲劳行为及塑性应变能

采用电解低钛铝合金、工业纯铝与Al-10Ti中间合金,制备了具有不同钛含量的电解加钛A356合金(EA356合金)和熔配加钛A356合金(MA356合金),研究了加钛方式和钛含量对A356合金的应变能密度和低周疲劳性能的影响。结果表明:4种合金均表现为明显的循环硬化行为;具有较高钛含量的E14、M14合金的循环硬化能力高于低钛含量的E10和M10合金;合金的塑性应变能密度受应变幅的影响且具有循环相关性;高应变幅时,塑性应变能较高但随循环周次变化较小;当应变幅较低时,合金的塑性应变能较小但变化较大,特别是塑性较好的E10和M10合金;无论是电解加钛还是熔配加钛,钛含量为0.1%的E10和M10合金的的塑性应变能密度和疲劳寿命均优于钛含量为0.14%的E14和M14合金;合金的疲劳寿命对加钛方式不敏感,在相同钛含量下,两种加钛方式的合金具有相近的低周疲劳寿命。     

Effects of Cobalt on the Sintering Behavior of Mechanically Activated Tungsten Powder

Increasing powder activity is a method to ac-celerate silltering process and imProve proPer-ties of materials. Powder activity includes sur-face actiVity depending on the particle size andshaPe, and crystal smicfore activity dependingon the faults and intemal stresses. The faultssuch as voids and dislocations in powder can beincreased by mechanical activation process(high-energy ball milling). This can lower thesintering temperatWe, shorten the silltering timeand imProve the properties of si…     

Effects of Pd substitution for Ni on corrosion performances of Mg_(0.9)Ti_(0.1)Ni_(1-x)Pd_x hydrogen storage alloys

1 Introduction MgNi-based amorphous hydrogen storage alloys have drawn much attention in the last ten years. Compared with AB5 or AB2 type electrode alloys, the alloy candidates for the negative electrode of Ni-MH batteries possess several advantages, su…     

热处理对新型Al-Mg-Si合金微观组织及性能的影响

对4种通过热力学计算优化选出的Al-Mg-Si合金进行了电磁搅拌及热处理试验研究。通过微观组织和性能的分析比较发现,电磁搅拌能显著改善合金的显微组织结构,为后续的热处理提供有利的显微组织条件,进而增强合金的时效强化效果,改善合金的塑性。同时发现,Mg、Si含量对合金的显微组织和性能具有不同的影响,这与合金不同的平衡凝固过程有关。该试验研究为进一步优化适合半固态成形的低成本高性能铝合金提供了依据。     

Economic net-shape forming of TiAl alloys for automotive parts

Alpha-case formations between investment molds and TiAl alloys were investigated for the economic TiAl alloys net-shape forming. In the case of TiAl alloys, there were no α-case formation reactions. There were neither interstitial nor substitutional α-case formations since TiAl alloys have both negligible solubility of oxygen and low activity in molten states. The fluidity of TiAl alloys is increased with mold preheating temperature since they have a peritectic reaction that appears in the form of envelopment, surrounding each particles of the primary constituent. The results of the investment casting of TiAl alloys confirm that the casting route in our study can be an effective approach for the economic net-shape forming of TiAl alloys.