熔体过热处理对Cu基块状非晶形成能力的影响及块状非晶的DSC研究

在水冷铜坩埚中采用铜模吸铸法制备出直径为3.0mm的Cu50Zr42Al8合金圆棒,研究了熔体过热处理对铜模吸铸法制备块状非晶合金的影响,表明通过熔体过热处理可以提高块状非晶的形成能力,并且存在一个最佳的过热温度。采用DSC技术对铜基成分为Cu50Zr42Al8块状非晶合金进行变温晶化动力学研究,结果表明,随着升温速率的增大,该合金的热稳定性参数和约化玻璃转变温度(Trg)均增大。     

Formation and crystallization of bulk Pd_(82)Si_(18) amorphous alloys

1　INTRODUCTIONMetallicglassisregardedasastatethatisofdis orderunlikecrystalalloyswith periodicatomstruc ture.Soitshowsexcellentcapabilitiesofsoftmag netism ,mechanics ,corrosionresistance ,etc .How ever ,mostofamorphousalloyswereproducedbyus ingrapidsolidificationmethodssuchassplatquench ing ,meltspinning ,andsoon ,withcharacteristiccoolingratesof 10 4 10 6 K/s .Becauseamorphousal loysarepreparedwithsilk ,powderandribbon ,itisgreatlylimitedinengineeringapplication .Recently ,severalbulk…     

Ni/Co比例及微量Dy对FeCoNiBSiNb块体非晶合金玻璃形成能力和磁性能的影响

采用水冷铜模吸铸工艺制备了一系列的(Fe0.5Co1-xNix)72B19.2Si4.8Nb4(x=0,0.05,0.1,0.15,0.2,0.25,0.3,0.4)块体非晶合金.并采用X射线衍射仪(XRD)、差热分析仪(DTA)、振动样品磁强计(VSM)测试了块体非晶合金的结构、热稳定性和软磁性能.探讨了不同Ni/Co比例及添加稀土元素Dy对FeCoNiBSiNb系合金玻璃形成能力(GFA)、热稳定性及磁性能的影响.结果表明:当x=0.05,0.1,0.15,0.2时可制备出直径2mm的非品合金棒,但不能获得3mm非晶合金棒,x=0.25,0.3,0.4均不能获得直径2mm的非晶合金棒,且随Ni/Co比例的增大,即随Ni含量的增加,热稳定性先增加,后逐渐减小,过冷液相区△Tx逐渐减小,非晶合金的玻璃形成能力呈下降趋势,非晶合金的饱和磁化强度(Ms)下降.添加1 at%Dy后,提高了合金的非晶形成能力,可制备出直径3mm的[(Fe0.5Co0.4Ni0.1)72B19.2Si4.8Nb4]99Dy1非晶合金棒,但合金的Ms下降.     

Nb对Fe-Co基合金非晶形成能力及磁性能的影响

利用铜模吸铸法制备(Fe0.5Co0.5)71-xNbxZr3Nd4B22(x=0~10)系块体合金,研究合金元素Nb的添加对该体系合金非晶形成能力(GFA)和磁性能的影响。结果表明,适当Nb的添加能有效提高合金的非晶形成能力。当Nb含量为5at%时,可获得具有完全非晶结构的块体非晶合金,该合金呈现典型的软磁性能,饱和磁化强度(Ms)为79 Am2/kg;合金的晶化温度(Tx)为957 K,晶化激活能E为538.30 kJ/mol。     

微量稀土Dy及Fe/Co比例对FeCoBSiNb块体非晶合金玻璃形成能力和磁性能的影响

采用铜模吸铸工艺成功制备了一系列的[(Fe_xCo_(1-x))_(0.72)B_(0.192)Si_(0.048)Nb_(0.04)]_(100-y)Dy_y(x=0.5,0.6,0.7,0.8,0.9;y= 0,1,2,3)块体非晶合金,并采用X射线衍射仪(XRD)、示差扫描量热分析仪(DSC)、振动样品磁强计(VSM)测试块体非晶合金的结构、热稳定性和软磁性能;分析了稀土元素Dy以及不同Fe/Co比例对FeCoBSiNb系合金玻璃形成能力(GFA)、热稳定性及磁性能的影响。结果表明:添加2at%的Dy后,合金的非晶形成能力提高,可制备出φ3mm的[(Fe_(0.5)Co_(0.5))_(0.72)B_(0.192)Si_(0.048)Nb_(0.04)]_(98)Dy_2非晶合金棒,但合金饱和磁化强度(M_s)下降;[(Fe_xCo_(1-x))_(0.72)B_(0.192)Si_(0.04)8Nb_(0.04)]_(98)Dy_2非晶合金随Fe/Co比例从5∶5增加至8∶2时,均能形成φ2 mm的非晶棒,但合金的非晶形成能力呈下降趋势,而其饱和磁化强度随铁含量的增大而提高。     

Zr55Al10Cu30Ni5-xPdx块状非晶合金的玻璃形成能力和热稳定性

用铜模铸造方法制备了不同尺寸的Zr55Al10Cu30Ni5-xPdx(x=0,1,3,5)块状非晶合金，采用X射线衍射（XRD）、扫描差热分析（DSC）和透射电镜（TEM）分别为Zr55Al10Cu30Ni5-xPdx块状非晶样品的结构、热稳定性和微观组织进行了研究。结果表明：x=1时，合金具有最高的过冷液相区（高达100K）及最大的热稳定性，而对合金的玻璃形成能力影响不大，这说明用适量的Pd代表Zr55Al10Cu30Ni5合金中的Ni会提高合金的热稳定性；x=3时，合金的热稳定性有所提高，但降低了合金的玻璃形成能力；x=5时，非晶合金的热稳定性和玻璃形成能力同时降低。     

Nd对Mg65Cu22Ni3Y10非晶形成能力及热稳定性的影响

利用楔形铜模铸造法成功制备了Mg65Cu22Ni3Y10-xNdx(x=0、2、4、5、6、8)块体非晶合金,采用XRD、DSC研究了Nd对该合金体系热稳定性和非晶形成能力(GFA)的影响。结果表明,当x=2、4时,Nd的添加可有效提高该合金的GFA和热稳定性;当Nd含量为2%(摩尔分数)时,合金具有最高的过冷液相区(ΔTx=61.5K)及最好的热稳定性;当x=5时,尽管过冷液相区(ΔTx=48.5K)最窄,但此时合金具有最强的非晶形成能力(Trg=Tg/Tl=0.568)和临界厚度(δmax=3.8mm);随着Nd的进一步增加(x>5),合金的玻璃形成能力降低。     

Preparation of AZ31 magnesium alloy strips using vertical twin-roll caster

A newly developed technology for manufacturing magnesium alloy strip,vertical twin-roll strip casting,has been described.This manufacturing process is easy to be facilitated in an economical way to manufacture wrought magnesium alloy strips. As an example,AZ31 magnesium alloy was used to investigate the appropriate manufacturing conditions for vertical twin-roll strip casting by varying the temperatures of the molten materials and rolling speeds.The effects of manufacturing conditions on forming quality were clarified in terms of roll speeds and casting temperature.In addition,microscopic observation and X-ray diffraction of the as-cast strips were performed.It has been determined that AZ31 alloy strip of 1-3 mm in thickness can be produced at a speed of 30 m/min by a vertical twin-roll caster.The microstructure of as-cast strip only containsα-phase(Mg)and no other phase,and the twin-roll casting process can effectively refine the grain size.The fine equiaxed grain of as-cast strips is beneficial to the plastic deformation of the strips,and it is also suitable for direct cold-rolling with a maximum cold-rolling reduction of 40%.     

Twin-roll strip casting of magnesium alloys in China

The development status of twin-roll strip casting for magnesium alloys in China was summarized as well as the new progress when several kinds of twin-roll strip casting technologies were developed and used.Horizontal twin-roll casting (HTRC) of magnesium alloys has attracted much attention and has been industrialized in China.Vertical twin roll casting(VTRC) of the magnesium alloys can reach a speed of higher than 30 m/min and its research and development are just beginning and exhibit exciting potential...     

AZ31镁合金薄带立式双辊铸轧试验研究

利用近终形双辊铸轧薄带新工艺快速凝固、动态直接成形的特点,直接制备镁合金薄带坯。研究了镁合金立式铸轧成形工艺及退火工艺,分析了不同工艺下的微观组织。结果表明:采用铸轧工艺很好的解决了坯料成形问题,同时细化晶粒,提高镁合金薄带坯的加工成形性能。经400℃,60 min退火,可以获得平均直径9～10μm分布均匀的等轴细晶组织。     

Micromodel of Simulation on Twin-Roll Continuous Casting Thin Strip Solidification Structure

在研究双辊连铸铝合金薄带工艺凝固过程的基础上,基于金属凝固的基本原理,建立双辊连铸铝合金薄带凝固的异质形核、枝晶尖端的生长动力学(KGT)、柱状晶向等轴晶生长的转变(CET)的解析模型,同时建立基于元胞自动机(CA)的双辊连铸铝合金薄带凝固组织的仿真模型,为双辊连铸薄带凝固组织形成的仿真模拟奠定基础,从而为双辊薄带连铸工艺提供一定的理论指导。同时利用铝合金双辊薄带连续铸轧组织凝固过程验证了数学模拟的可行性。     

Superplastic Response of Continuously Cast AZ31B Magnesium Sheet Alloys

Magnesium sheet is typically produced for commercial applications with the traditional DC-ingot casting method. As a result of the hexagonal close-packed crystallographic structure in magnesium, multiple rolling passes and annealing steps are required to reduce the thickness of the ingots. Thus, high fabrication costs characterize the creation of magnesium sheet suitable for common forming operations. Recently, continuous casting (CC) technology, where molten metal is solidified directly into sheet form, has been applied to magnesium alloys; this method has shown the potential to significantly reduce the cost of fabricating magnesium sheet alloys. In order to understand the viability of the CC process, a study was conducted to investigate the superplastic potential of alloys produced by this method. This study focused on AZ31B Mg that was continuously-cast on twin-roll casters from three different suppliers. These three materials were compared with a production DC-cast AZ31B alloy in terms of microstructure, elevated-temperature tensile properties, and superplastic forming response. The data from this study found that microstructural features such as grain size and segregation can significantly affect the forming response. Additionally, the CC alloys can have equivalent or superior SPF response compared to DC-cast alloys, as demonstrated in both elevated temperature tensile tests and superplastic forming trials using a rectangular pan die.     

Castability of Cu54Ni6Zr22Ti18 bulk amorphous alloy

Castability, in a narrow sense, means the formability of a particular liquid metal into a desired shape by transformation from liquid to solid. Considering the importance of recycling, the reuse of returned scrap should be related to castability. In addition, glass forming ability should also be studied for bulk amorphous metals, as it is very closely related to crack formation during casting. This paper reports a study on the castability of Cu-base bulk amorphous alloy made by conventional vacuum induction melting. The effects of specimen thickness, number of remeltings, and mold temperature were investigated. A test mold for thin plate specimens was designed in order to evaluate the liquid formability of the alloy. Mold filling was good for 2 mm specimens; however, many cracks were observed after cooling. While the mold cavities were not fully filled for 1 mm specimens, no cracks could be found. The glass forming ability also became worse with increasing number of remeltings; this worsening is believed to be caused by the increase in oxygen content.     

Effects of Ce and Mm additions on the glass forming ability of Al–Ni–Si metallic glass alloys

The effects of Ce and Mm contents on the glass forming ability (GFA) of melt-quenched Al_89−xNi₈Ce_xSi₃ and Al_89−xNi₈Mm_xSi₃ (x = 0, 1, 3, 5, 7 at.%) alloys have been systematically investigated by X-ray diffraction (XRD) and differential scanning calorimetry (DSC). According to the XRD and DSC results, both Ce and Mm elements can enhance the GFA and thermal stability of the Al–Ni–Si alloys. Moreover, only the x = 5 and x = 7 alloys are totally amorphous in both systems quenched at the wheel speed of 36.6 m/s. Compared with amorphous Al₈₄Ni₈Ce₅Si₃ alloy at different cooling rates, amorphous Al₈₄Ni₈Mm₅Si₃ alloy has higher GFA which is considered to have relation to the different atomic structure of the amorphous alloy.     

Fe-Co-B-Si-Nb-Cr软磁块体非晶合金的制备及性能

采用微合金化技术,用铜模铸造法制备Fe-Co-B-Si-Nb-Cr块体非晶合金。借助于XRD、TEM、DSC、DTA和VSM表征该玻璃合金系的玻璃形成能力和软磁性能;借助动电位极化、宏观压缩试验和纳米压痕技术测试该玻璃合金系的腐蚀和力学性能。结果表明:Cr元素的加入,尽管稍微降低了Fe-Co-B-Si-Nb玻璃合金的形成能力,但却明显改善了它的软磁性能、力学性能和腐蚀性能;用铜模铸造法,可获得最大直径为4mm的玻璃棒;这些块体非晶表现出高饱和磁感应强度(0.81～1.04T)、极低的矫顽力(0.6～1.6A/m)、200～215GPa的杨氏模量、约2%的弹性应变和0.7%的塑性应变,还拥有超高的断裂强度(3840～4043MPa);用深度敏感纳米压痕技术研究了{[(Fe0.6Co0.4)0.75B0.2Si0.05]0.96-Nb0.04}96Cr4块体非晶合金的室温塑性变形;该合金的纳米压痕变形行为与加载速率有关:在0.75～3mN/s加载速率下,发现了显著的锯齿流变;当增大到6mN/s时,锯齿流变逐渐消失。另外,当Cr含量(原子分数%,下同)从x=0增加到x=4时,该块体非晶合金在0.5mol/LNaCl...     

Amorphous phase formation in a Ni−Zr−Al−Y alloy system

Quaternary Ni-based amorphous alloys containing only metallic elements were developed through systematic alloy design. The importance of the phase equilibria information for the development of amorphous alloys was demonstrated through experimental results. Ni−Zr−Al ternary alloys having low liquidus temperature tend to have high GFA. Partial replacements of Zr with Y in the ternary alloys significantly enhanced the GFA of the quaternary alloys. The alloy Ni₆₀Zr₂₅Al₈Y₇ could be cast into a fully amorphous rod through an injection casting method. Since most Ni-based amorphous alloys reported to date contain non-metallic elements, the Ni-based amorphous alloys developed in the alloy system Ni−Zr−Al−Y are of interest.     

Role of addition in formation and properties of Zr-based bulk metallic glasses

A various multicomponent bulk metallic glasses (BMGs) were prepared at a low cooling rates of 1–100 K/s. The effects of various additions on the glass forming ability (GFA), properties and thermal stability of the alloy systems were investigated. The structural and properties changes of the BMGs upon addition were studies using X-ray diffraction, differential scanning calorimetry, density measurement, and acoustic measurement. It is found that the proper elemental addition can significantly improve the GFA and properties of the bulk glass-forming alloys. The addition is an effective way for improving GFA, and properties of the bulky glass-forming alloys. The roles of the additions in the glass formation, properties and crystallization are discussed.     

Ni对Mg-Cu-Tb非晶合金形成及力学性能的影响

利用熔体铜模喷铸法制备出直径为3 mm的Mg65Cu25-xNixTb10(x=0,5,10)非晶合金。利用X射线衍射、差热分析、压缩实验分析和扫描电镜分析了添加Ni元素对Mg-Cu-Tb非晶合金形成能力及力学性能的影响。研究表明:随着Ni含量的增加,合金的玻璃转变温度Tg增大;开始结晶温度Tx降低;过冷液相区宽度ΔTx减小,约化玻璃转变温度Trg从0.562降至0.530,非晶形成能力逐渐降低。压缩实验结果表明:当Ni含量增加到5%时可以明显提高Mg-Cu-Tb-Ni非晶合金的断裂强度。     

Foundation of bulk amorphous alloy database

During the past 10 years, research about bulk amorphous alloys has made some progress and a great quantity of data has been published. One of the main studying aims is to find a series of alloys with high glass-forming ability so they can be fabricated by conventional casting or high-pressure die casting techniques. However, traditional “trial and error’’ methods have still been used to explore new bulk amorphous alloy systems. It is time to design bulk amorphous alloy compositions by computer aided design referring to condensed state physics, computational materials science and database. A database has been assembled with a lot of documents and data about bulk amorphous alloys. It has convenient inquiry, index, and modification functions. In the database, disorder data have been systemized and regularized, and can be directly used by other computational programs. It concluded that the bulk amorphous alloys database is especially helpful to research and design bulk amorphous alloys.     

Si的添加对Zr-Fe-Ou合金系统的组织和力学性能的影响

在Zr-Fe—Cu合金中添加Si,利用铜模铸造法制备出直径为3mm的Zr基非晶／晶体复合材料。采用X射线衍射（XRD）、扫描电子显微镜（SEM）和微机控制电子式万能试验机等技术手段,研究了Si元素的添加对Zr-Fe-Cu合金的微观结构、非晶形成能力、压缩力学性能以及断口形貌的影响。结果表明：Si元素对非晶材料的性能与结构有很大的影响,能够提高合金的强度和塑性。