Viscosity of In and In-Sballoys

The dynamic viscosity of pure In, In-1%Sb (mass fraction, so as the follows) alloy, In-55%Sb hypoeutectic alloy and In-69.5%Sb eutectic alloy was measured by using a torsional oscillation viscometer at different temperatures above liq-uidus. The experimental results show that the viscosity of these melts decreases with increasing temperature. The anomalous change of viscosity occurs at about 430 and 470℃in pure In melt. The variation of viscosity with temperature well meets exponential correlation and no anomalous change occurs in measured temperature range in the In-1%Sb alloy melt. A transition occurs at about 800℃ in both of In-55%Sb and In-69.5%Sb alloy melts. The sudden change of viscosity suggests the structure change of melts. DSC (differential scanning calorimetry) curves of In-1%Sb alloy during heating and cooling were measured, and the results show that no structural variation in In-1%Sb alloy melt was testified further. In addition, the viscosity of In melt decreases with the addition of1%S     

金属熔体原子团簇的微观热收缩机制探讨

以多种纯金属及合金的X射线衍射实验结果为基础,结合理论分析,从自由体积的角度探讨金属熔体原子团簇的微观热收缩现象,进一步揭示微观热收缩的本质及机制:熔体中原子团簇的微观热收缩,是熔体中自由体积膨胀较之宏观体积膨胀更为严重的结果,团簇结构的变化是导致其出现热收缩的根本原因。     

热历史对In-55wt%Sb亚共晶合金熔体粘度的影响

利用回转振动粘度仪在液相线以上较大温度范围内,测量了In-55%Sb（质量分数）亚共晶合金熔体在不同的升降温过程中的粘度.实验结果表明,熔体经历的热历史对其粘度具有显著的影响.熔体在降温过程中的粘度高于升温过程中,在过热100℃后的降温过程中熔体的粘度较之无过热的降温过程中要低.在不同的热过程中,粘度发生转折变化的温度不同,在升温过程中,发生在850℃左右,在过热100℃和无过热的降温过程中,分别发生在750℃和650℃左右.熔体粘度的突变反映了熔体结构在相应温度的突然变化.     

电脉冲孕育处理对Al-5%Cu合金液态结构的影响

利用高温X射线衍射仪对经电脉冲孕育处理的Al?5%Cu合金液态结构进行表征。结果表明：在经电脉冲孕育处理的熔体中,含 Cu 的铝团簇数量明显增加,由于相关原子半径和配位数的减小而使这些团簇呈现某种热收缩状态。这种液相结构将使最终的凝固组织中富Cu相更趋于均匀分布。DSC测试表明,经电脉冲孕育处理的液相在结晶过程中,其过冷度是未处理液相的2.36倍。可以确定,电脉冲处理后的Al?5%Cu熔体中原子团簇的变化与先前提出的纯金属电脉冲孕育处理机理模型存在明显差异。     

Cu的添加对X80钢热浸法渗铝层组织的影响

通过在热浸镀铝熔池中添加Cu元素,改善X80钢热浸法渗铝层的组织。在不同的温度下进行扩散退火试验,利用扫描电镜和X射线衍射仪研究退火温度和铜元素对渗层组织的作用机理。采用Smile View软件对渗层厚度进行测量。结果表明,在热浸法渗铝时,Cu的添加可以使合金层/X80钢基体界面间的舌齿状形态缩小,使得界面间反应更均匀。当Cu的添加量为1%(质量分数)时,脆性的Fe₂Al₅合金层的厚度最小。随着扩散退火温度的升高,Cu添加量为1%的试样渗层的界面均匀性增加;扩散退火温度≥600℃时,渗层中开始出现极薄的FeAl相层;扩散退火温度≥650℃时,自由层消失,渗层中出现均匀的FeAl层且渗层外侧出现孔洞;扩散退火温度为700℃时,FeAl层中部出现孔洞带,且渗层外侧出现大孔洞。在热浸镀铝熔池中加入1%Cu元素可以使扩散退火过程中Al原子和Fe原子间的迁移速率差值减小,进而降低Al原子和Fe原子间的浓度梯度。原子间浓度梯度的降低,使得界面间反应更均匀,从而避免渗层中孔洞的出现。     

Bi-20%Sb合金不同熔体状态下的凝固行为及组织

前期研究发现,升温过程中Bi-20%Sb合金熔体在829～1107℃区间存在不可逆的电阻率温度异常行为。据此,分别选取700℃和900℃进行等温电阻率试验,在700℃保温电阻率随时间无变化,而在900℃保温过程中电阻率在37～54min发生了明显降低,揭示熔体结构状态发生了改变。根据这一结果进行凝固试验,发现在相同的冷却条件下经历过熔体结构转变试样的冷却速度较慢,凝固组织明显细化;两种熔体状态下的过冷度与冷却速率分别满足分段线性关系;两种熔体状态下单位面积晶粒数和冷却速率均满足良好的线性关系。凝固过冷度增加,是因为合金熔体在结构转变后原子团簇变得更加细小均匀,需要降到更低温度时才可以发生形核。冷却速度变慢,是因为热导率随着混乱度的增加而减小,经历过熔体结构转变的熔体在降温的过程中热导率减小。     

Calculation of free energy of Al-Cu-Li alloy under electric field

Based on Thomas-Fermi model, the interior potential boundary condition with the effect of electric field was defined, the calculation method of free energy for atom cluster under electric field was established. The change of free energy of Al-Cu-Li alloy under the effect of electric field was calculated quantitatively. It is shown that： near the zero electric field and the side of positive electric field, the free energy of Cu4LiAl7 compound at aging temperature 460 K is higher than that of free energy at solid solution temperature 725 K, but once the negative electric field increases to certain degree there will be opposite result. Under the effect of electric field, at 725 K the free energy of Cu4LiAl7 is higher than that of Al-1.0%Li-4.0%Cu, and at 460 K the free energy of compound is lower than that of solid solution. When the copper content in the Al-Li-Cu solid solution is below 5%, under the effect of electric field the free energy of solid solution increases gradually with the increasing of copper content, but the increasing amplitude reduces with the increasing of copper content. The free energy of binary solid solution increases with the addition of lithium, and with the increasing of electric field intensity the free energy margin of two kinds of solid solution becomes bigger.     

热压烧结Fe3Si-Cu在NaOH溶液中的腐蚀行为

以原子比为3∶1的Fe粉和Si粉球磨20 h后与一定量的Cu粉混合,在(1000±30)℃,20 MPa的压力下热压烧结制备了致密的Fe3Si-Cu复合材料。通过浸泡腐蚀和电化学腐蚀两种方法研究加入不同质量分数Cu(5%,10%)的Fe3Si-Cu复合材料在0.6、0.7和0.8 mol/l的NaOH溶液中的腐蚀行为。结果表明,两种材料在不同摩尔浓度的NaOH溶液中的腐蚀是一种均匀的全面腐蚀。复合材料中的Fe3Si和Cu两相在NaOH溶液中组成一腐蚀电池,其中Fe3Si为阳极发生腐蚀,Cu作为阴极得到保护;Fe3 Si-5%Cu复合材料在NaOH溶液中的自腐蚀电位随NaOH浓度的增加而增加,自腐蚀电流在0.7 mol/l的NaOH溶液中最低;Fe3 Si-10%Cu在三种浓度的NaOH溶液中的自腐蚀电位相差较小,自腐蚀电流在浓度为0.6 mol/l的NaOH溶液中最小,在0.7mol/l的NaOH溶液中最大。     

Cu含量及T6处理对电力金具用铝合金组织性能的影响

探究了Cu含量与时效工艺对Al-Cu-Mg-Si系合金显微组织、力学性能以及耐腐蚀性能的影响。研究表明,随Cu含量的增加,铸态铝合金中Al₂Cu相数量增加、尺寸不断增大,形貌由点状转为粗网状,铸态铝合金的强度也随之提升,耐蚀性能下降。在180 ℃×(4~28) h时效区间内,整体上合金硬度先上升后下降,0.5%Cu、1.5%Cu合金在8 h时达到峰值,2.5%Cu合金在12 h时达到峰值。530 ℃固溶+180 ℃×8 h时效后,铝合金中析出Al₂Cu相,随着Cu含量的增加,Al₂Cu相的含量增加,硬度显著上升,2.5%Cu含量的合金抗拉强度达到最大值325.0 MPa,屈服强度达到258.8 MPa,伸长率为4.5%,其强度与传统的电力金具用铸铁相当。     

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。     

Thermophysical Properties of Cu-Matrix Composites Manufactured Using Cu Powder Coated with Graphene

Compact Cu matrix composites reinforced with graphene were prepared by thermochemical processes and cold isostatic pressing. Thermophysical properties were investigated using laser flash analysis, differential scanning calorimetry, and dilatometry. From the results of the measurements, it follows that within the entire investigated temperature range, both the thermal diffusivity and the calculated values therefrom of the thermal conductivity of copper-graphene composites change according to the temperature changes. Above 500 °C, abnormal decrease of the thermal diffusivity was registered for sample prepared from pure copper powder. In this case, the elevated temperature of test could cause sintering of copper particles, which were not coated by graphene. The as-received composites had higher thermal diffusivity and the thermal conductivity at the room temperature in comparison to the material obtained by standard pressing of pure copper powder. However, the production methods of some samples could cause their partial sintering. Based on the study, it could not be concluded that graphene only has impacts on the thermophysical properties.     

Effect of Nd and La on surface tension and wettability of Sn-8Zn-3Bi solders

Maximum bubble pressure measurement was employed to evaluate surface tension of Sn-8Zn-3Bi- （0-0.15）Nd and Sn-8Zn-3Bi-（0 -0. 15）La solder melts. Wetting balance method was used to measure wetting force and wetting time on Cu substrate of the two group solders. The experimental results show that minute amount of Nd or La addition to Sn-8Zn-3Bi solder causes significant decrease of the surface tension of the solder melts at 200 - 240 ℃ and Nd addition is more effective on reduction of surface tension than that of La. Nd or La addition has the effect on enhancing the wetting force of the solder melts on Cu substrate, which results from the de- crease of interracial tension between the solder melt and Cu substrate. The wetting force reaches the maximum when 0.1% Nd is added to the base alloy. The contact angle between Sn-8Zn-3Bi base solders and Cu substrate decreases with the addition of Nd or La and the minimum of the contact angle is obtained from the solder with 0.1% Nd addition.     

Ga-Sb合金熔体的黏滞行为

利用熔体黏度仪系统研究了不同成分Ga-Sb熔体的黏度变化规律。结果表明,Ga-Sb熔体的黏度总体趋势是随温度的降低而增大,黏度变化曲线基本呈指数变化。其中Ga36.5Sb63.5熔体黏度随温度的变化在830℃左右出现突变,将黏度曲线分成低温区和高温区两部分。根据该熔体结构变化的特点,对有关试验结果进行了分析讨论。     

Dependence of viscosity of Cu9In4 intermetallics melt on thermal history

The temperature dependence of the dynamic viscosity of Cu9In4 intermetallics melt has been investigated in five kinds of different heating and cooling processes with a torsional oscillation viscometer, It has been found that the viscosity of all Cu9In4 intermetallics decreases with increasing temperature in five kinds of different thermal processes. Thermal history has considerable effect on the viscosity. The viscosity in the cooling process with high superheating is greater than that in the cooling process with low superheating. The viscosity in the heating process is greater than that in the cooling process. No anomalous change in viscosity is measured in three kinds of cooling processes with low superheating. The anomalous change occurs at about 1050℃ in cooling with high superheating and at 800℃ in heating. Furthermore, the structural variation in different thermal processes has also been discussed on the basis of the change in viscosity and DSC analysis.     

Effect of indium addition in Sn-rich solder on the dissolution of Cu metallization

An investigation has been carried out to study the dissolution of the Cu pad of the ball-grid-array (BGA) substrate into the molten Sn–9%In–3.5%Ag–0.5%Cu, Sn–3.5%Ag–0.5%Cu and Sn–0.7%Cu (wt.%) solder alloys. A fixed volume of BGA solder ball (760 μm dia) was used on a 13 μm thick Cu pad with a diameter of 650 μm. The dissolution measurement was carried out by measuring the change of Cu pad thickness as a function of time and temperature. Scanning electron microscopy was used to examine the microstructure of the solder joint and to measure the consumed thickness of Cu. The dissolution of Cu in Sn–3.5%Ag–0.5%Cu solder is higher than the other two lead-free solders. The presence of indium in the solder plays a major role in inhibiting the consumption of Cu in the soldering reaction. The intermetallic compounds (IMCs) formed at the Sn–9%In–3.5%Ag–0.5%Cu/Cu interface are determined as a scallop-shaped Cu₆(Sn, In)₅. Bulk of the Sn–9%In–3.5%Ag–0.5%Cu solder also contains Cu₆(Sn, In)₅ and Ag–In–Sn precipitates embedded in the Sn-rich matrix. It is also found that more Cu-containing Sn–0.7%Cu solder shows lower Cu consumption than Sn–3.5%Ag–0.5%Cu solder at the same heat treatment condition.     

纯铜深层渗铝内氧化的组织及性能

为提高铜质件的耐热性和耐磨性,采用纯铜深层渗铝内氧化试验方法制备了Al2O3/Cu 表面复合材料,研究了纯铜深层渗铝内氧化的金相组织特征及性能,结果表明: 与纯铜试样相比,深层渗铝内氧化试样的抗磨粒磨损性能和抗粘着磨损性能分别为纯铜试样的1.85倍和9.4倍,抗热疲劳性大幅度提高,经250次热循环后,内氧化试样质量损失率为纯铜试样的0.88%.这种特性使得纯铜深层渗铝内氧化Al2O3/Cu 复合材料在高温服役条件下更适合用作冶金设备用传热铜材料.     

Back Matter

The present work was performed on twenty-one alloys containing Al-11.5 wt% Si, with magnesium (Mg) in the range of 0.1–0.4 wt%, and copper (Cu) in the range of 1.0–3.0 wt%. Fluidity measurements and thermal analysis for each of these alloy melts were carried out. The alloys were cast in the form of tensile test bars. The test bars were solution heat treated at a temperature of ~500°C for 8h, then quenched in hot water (60°C), followed by artificial ageing at 155°C for 5 h, and then cooling in air. The effects of Mg and Cu additions on the tensile properties, depression in the Al-Si eutectic temperature, and microstructural characteristics (Si and Cu-phase particle characteristics and morphology) have been discussed in detail. The results show that the addition of Mg decreases the fluidity and the eutectic Si temperature. While addition of Cu also decreases the eutectic temperature, the fluidity, however, is increased. The presence of Mg and Cu decreases the modifying effect of Sr on the Si particles due to an increase in the solidification time, as well as the Sr, Mg, Cu interactions that occurs as a result of these additions. Mg additions in the range of 0.1–0.4 wt% increase YS (from 22% up to 94%) and UTS (from 7% up to 52%) and decrease the percent elongation (40%) depending on the Cu content of the alloy, i.e., the higher the Cu content, the lower the increase in strength. Addition of Cu has a similar effect on YS and UTS at alloy Mg levels of 0.1 wt% only, with no effect at higher Mg values, while elongation continuously decreases. The volume fraction of Al₂Cu phase increases by approximately 0.76% for every 1 wt% increase in Cu. This observation is important in the selection of the appropriate solution heat treatment regime in order to avoid incipient melting.     

Al-Si合金熔体热处理的结构转变

用示差扫描量热分析了Al-Si合金温度处理的熔体结构变化规律及结构变化温度。结果表明,在升温阶段的Al-7%Si亚共晶、Al-12%Si共晶及Al-20%Si过共晶合金的熔体中均存在额外的热效应,范围均在798～850℃之间,额外热效应温度范围与含硅量无关,结构转变焓值随合金的硅含量增加而增加,氢含量不影响结构转变的温度;而在降温过程中仅在Al-20%Si过共晶合金中发现了额外热效应,额外热效应的出现及温度范围取决于降温速度。分析认为,升温阶段的额外热效应体现了Al的熔体结构变化,降温阶段的额外热效应与熔体中的Si-Si原子团簇的行为有关。     

含Cu的Al-Mg-Si合金微观组织及耐热性能的研究

主要研究了添加铜元素对6082 Al-Mg-Si合金微观组织及耐热性能的影响。研究表明,添加Cu提高了Al-Mg-Si合金的峰值硬度并缩短了合金达到峰值硬度的时间;添加0.6%Cu的合金在170℃时效4 h后,合金中形成了板条状析出相Q′;在250℃等温不同时间后,含Cu合金的硬度明显高于不含Cu的合金,说明添加Cu可以提高Al-Mg-Si合金的耐热性能。     

Interfacial phase formation of Al-Cu bimetal by solid-liquid casting method

The solid-liquid method was used to prepare the continuous casting of copper cladding aluminium by liquid aluminum alloy and solid copper, and the interfacial phase formation of Al-Cu bimetal at different pouring temperatures (700, 750, 800 ℃) was investigated by means of metallograph, scanning electron microscopy (SEM) and energy dispersive spectrometry (EDS) methods. The results showed that the pouring temperature of aluminum melt had an important influence on the element diffusion of Cu from the solid Cu to Al alloy melt and the reactions between Al and Cu, as well as the morphology of the Al-Cu interface. When the pouring temperature was 800 oC, there were abundant Al-Cu intermetallic compounds (IMCs) near the interface. However, a lower pouring temperature (700 ℃) resulted in the formation of cavities which was detrimental to the bonding and mechanical properties. Under the conditions in this study, the good metallurgical bonding of Al-Cu was achieved at a pouring temperature of 750 ℃.