铜合金的流变性能

在自行研制的高温合金流变性能测试装置上，进行了固液共存区铜合金流变性能的研究。测试了合金在不变应力作用下不同温度时的应变－时间曲线，据此曲线建立了铜合金在液固共存态的流变性能模型和本构方程，分析了凝固过程中温度变化时铜合金流变性能与质点间作用力及合金结构的改变之间的关系。     

铸钢流变性能的实验研究

本文在自行研制的高熔点合金流变性能测试装置上，进行了液态及固液共存区钢的流变性能的实验研究。测试出合金在各温度下的γ─ｔ曲线，据此建立了合金在液态及固液共存区的流变性能机械模型及本构方程，分析了铸钢流变性能与凝固过程中钢的结构变化及质点间作用力的内在联系。     

A1－4．87％Si合金准固态流变性能研究

用自行研制的合金准固流变性能测试装置实测了Ａｌ－４．８７％Ｓｉ合金准固态温度下的流变曲线，由此建立了该合金的流变物理模型和应力－应变本构方程。根据实验结果，计算了该合金的流变特性本数位。并对结果进行了讨论和分析。     

半固态LY11合金的压缩变形

研究了变形温度和应变速率对半固态LY11合金变形行为和微观组织的影响.研究结果表明:在液固温度区间变形时,变形温度、应变速率对半固态LY11合金的流变应力峰值影响显著,对稳态流变应力影响较小.对微观组织的影响是:随着变形温度的升高和应变速率的降低,固相晶粒尺寸增大,但仍保持初始的近球状.在半固态合金的压缩过程中,随着工艺参数的变化,占主导地位的变形机制也随之变化.     

铸钢流变性能的实验研究

本文在行研制的高熔点合金流变性能测试装置上，进行了液态及固液共存区的流变性能的实验研究，测试了合金的各温度下的γ－ｔ曲线，据此建立了合金在液态及固液共存区的流变性能机械模型及本构方程，分析了铸钢流变性能与凝固过程中结构质点间作用力的内在联系。     

对半固态合金流变性能模型的讨论

通过对铸造合金流性能参数随温度的上升而减小的机理分析，对半固态合金流变性能的六元件模型提出了商讨的意见。     

Al—4.87%Si合金准固态流变性能研究

用自行研制的合金准固流变性能测试装置实测了Ａｌ－４．８７％Ｓｉ合金准固态下的流变曲线，由此建立了该合金的流变物理模型和应力－应变本构方程。根据实验结果，计算了该合金的流变特性参数值，并对结果进行了讨论和分析。     

Ti14合金半固态压缩中的应力松弛现象和变形机制的研究

利用Gleeble1500热/力模拟机对Ti14合金进行了半固态压缩变形试验,研究了该合金在应变速率为5×10-2s-1和5×10-1s-1,变形温度为1273~1423K条件下的流变应力变化规律,分析了该合金半固态下应力松弛发生的条件和原因,并讨论了温度、应变速率和变形机制之间的耦合关系。结果表明:温度和应变速率对流变应力有显著的影响,流变应力随着变形温度的升高和应变速率的降低而降低,宏观应力松弛发生在固相含量区间为0.95~0.98,主要是因为液相的增加减少了晶粒间的"固相桥"作用。由于液相在变形中的渗漏,Ti14合金在1273~1423K半固态变形的应变速率试验值远远小于Iwasaki润滑流动机制(固液混合变形机制)所需的理论值,说明在所测试的半固态区间内合金仍以固相粒子变形为主,固液混合变形为协调机制。     

Ti14合金半固态压缩中的应力松弛现象和变形机制的研究

利用Gleeble 1500热/力模拟机对Ti14合金进行了半固态压缩变形试验,研究了该合金在应变速率为5×10-2 s-1和5×10-1 s-1,变形温度为1273～1423 K条件下的流变应力变化规律,分析了该合金半固态下应力松弛发生的条件和原因,并讨论了温度、应变速率和变形机制之间的耦合关系.结果表明:温度和应变速率对流变应力有显著的影响,流变应力随着变形温度的升高和应变速率的降低而降低,宏观应力松弛发生在固相含量区间为0.95～0.98,主要是因为液相的增加减少了晶粒间的“固相桥”作用.由于液相在变形中的渗漏,Ti14合金在1273～1423 K半固态变形的应变速率试验值远远小于Iwasaki润滑流动机制(固液混合变形机制)所需的理论值,说明在所测试的半固态区间内合金仍以固相粒子变形为主,固液混合变形为协调机制.     

半固态A356合金的瞬态流变行为及半固态压铸研究

采用自行研制的流变装置研究了不同初生相形态半固态A356合金的瞬态流变行为,建立了瞬态流变本构模型;通过设计制造的坯料感应加热系统研究了加热过程中半固态合金的组织演化规律;借助模拟仿真技术确定模具浇注系统和合适的压射条件;对传统压铸机进行改造,生产出高质量的半固态触变成形样件.结果表明,初生相形态和切变机制对半固态合金的瞬态流变行为有显著影响;随合金坯料在液固温区停留时间增加,合金坯料产生组织变化和蠕变,将对后续的成形过程造成影响.     

RHEOLOGICAL PROPERTIES OF SEMI-SOLID Al-Si ALLOY IN SOLID-LIQUID ZONE

ＲＨＥＯＬＯＧＩＣＡＬＰＲＯＰＥＲＴＩＥＳＯＦＳＥＭＩＳＯＬＩＤＡｌＳｉＡＬＬＯＹＩＮＳＯＬＩＤＬＩＱＵＩＤＺＯＮＥ①ＣｈｅｎＸｉａｏｙａｎｇ，ＭａｏＷｅｉｍｉｎ，ＺｈｏｎｇＸｕｅｙｏｕＳｃｈｏｏｌｏｆＭａｔｅｒｉａｌｓＳｃｉｅｎｃｅａｎｄＥｎ...     

铸钢在凝固区的流变行为SCIEI

用自行设计的流变性能测定仪测量了624钢(32MnNiMoCu)在凝固区内的应力、应变关系。建立了该钢的流变模型、本构方程并确定了流变特性参数。为开展铸钢的应力、应变和热裂纹的计算机数值模拟提供了理论基础及计算数据。     

RHEOLOGICAL BEHAVIOURS OF CAST STEEL DURING SOLIDIFICATION

The stress-strain relation for cast low alloy carbon steel at solidification temperature hasbeen examined by the authors' own desingned apparatus for rheological propertiesmeasurement.The rheology model,the stress-strain constitutive equation and the rheologicalparameters therefrom of the cast steel were proposed.Thus the theoretical basis and calcula-ting data for computerized s#nulation on the stress-strain relation and thermal cracking ofthe cast steel were suggested.     

爆炸焊接及镶铸Al的Al/Cu/钢复合板的界面特征

采用固-液镶铸法实现了Cu／50CrV复合板与铝合金LD10液的复合，利用扫描电镜对镶铸复合板和Cu／50CrV复合板界面的组织结构进行了比较和研究。结果表明：Al/钢复合界面与Cu／钢复合界面具有相似的波状界面结构；镶铸铝合金／钢的铝合金基体区的组织类似于铝合金加Cu的铸造组织，过渡区相当于是原铜／钢过渡区的“解体”，其中的组织、相成分都受原过渡区结构的影响，钢基体上脱落的颗粒的组织结构发生了很大的变化；要获得良好的界面结构，需要爆炸焊接复合板的优化设计。     

Al-Zn对称成分Spinodal分解合金的组织、结构与相成分

利用组织分析方法和X射线衍射分析, 研究了Al-Zn对称成分Spinodal分解合金的组织、结构与成分. 结果表明, Al-Zn对称成分合金经固溶处理后可获得单相组织, 但该组织在室温下将发生Spinodal分解和Zn的析出. 在钢模铸造的快速冷却条件下, 该合金的相组成已经接近于平衡态, 但存在较多的缺陷和较大的成分不均匀性. 利用实测晶格常数的方法可以近似确定Spinodal分解和不连续析出等高分散度两相组织中富Al固溶体的相成分.     

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 ℃.     

Phase-field simulation of solidification dendritic segregation in Ti-45Al alloy

The microstructures and mechanical properties of Ti Al alloys are directly linked to micro-segregation which cannot be avoided during solidification. So a thorough understanding of the micro-segregation should be a great help to further enhance the mechanical properties of the cast products. Theoretical analysis and experiments have been used to predict the micro-segregation, but it is very difficult to observe and determine the dendritic segregation in the micro region. Phase-field method has been employed for the simulation of dendritic growth. However, due to the complicated quasi-sub regular solution model for Ti-45Al(at.%) alloy, the classic phase-field models have difficulty to deal with the free energy. In this work, a phase-field model by linking thermodynamic calculation was used to simulate solidification dendritic segregation of Ti-45 Al alloy for Liquid→Liquid+β(Ti). The free energies of solid phase and liquid phase for Ti-45 Al alloy were calculated by Thermo-Calc and then coupled with the phase-field equations. The simulation results show the dendritic morphology and Al content variations between liquid and growing solid phase for Ti-45 Al alloy. With the growth of the β(Ti), dendritic segregation is formed in the liquid and solid phases due to the solute partitioning and rejection into the liquid. As a result, the dendrite arms are depleted of Al element, while the inter-dendrites are enriched. The dendritic tip growth velocity decreases with the progress of solidification, whereas the segregation ratio increases.     

Microstructure and mechanical properties of Zr-Cu-Al bulk metallic glasses

Zr49Cu46Al5 and Zr48.5Cu46.5Al5 bulk metallic glasses（BMGs） with diameter of 5 mm were prepared through water-cooled copper mold casting. The phase structures of the two alloys were identified by X-ray diffractometry（XRD）. The thermal stability was examined by differential scanning calorimetry（DSC）. Zr49Cu46Al5 alloy shows a glass transition temperature, Tg, of about 689 K, an crystallization temperature, Tx, of about 736 K. The Zr48.5Cu46.5Al5 alloy shows no obvious exothermic peak. The microstructure of the as-cast alloys was analyzed by transmission electron microscopy（TEM）. The aggregations of CuZr and CuZr2 nanocrystals with grain size of about 20 nm are observed in Zr49Cu46Al5 nanocrystalline composite, while the Zr48.5Cu46,5Al5 alloy containing many CuZr martensite plates is crystallized seriously. Mechanical properties of bulk Zr49Cu46Al5 nanocrystalline composite and Zr48.5Cu46.5Al5 alloy measured by compression tests at room temperature show that the work hardening ability of Zr48.5Cu46.5A15 alloy is larger than that of Zr49Cu46Al5 alloy.     

Effects of Solution Treatment on the Microstructure and Mechanical Properties of Al-16.9Si-4.5Cu-0.15Mg Alloy

In this paper, the microstructure and mechanical properties of Al-Si-Cu-Mg casting alloy under different solution conditions were investigated by optical metallographic and mechanical property test. The results show that the cast alloys were composed of α-Al, primary Si, eutectic Si, Al2Cu and Al7Cu2Fe phases. Three changes took place during solution treatment: Firstly, with the increase of solution temperature and the solution holding time extension, more and more Al2Cu phase was dissolved into the matrix; Secondly, with the increase of solution temperature and the solution holding time extension, morphology of eutectic Si, Al7Cu2Fe and other insoluble phases changed into more round; Thirdly, at the fixed solution temperature, if the solution time extended too long, it would cause grains, eutectic Si and other insoluble phases aggregated and coarsened. About mechanical properties, when the solution time was fixed, the hardness, tensile strength and the yield strength of the Al-Si-Cu-Mg alloy treated by T6 enhanced while the solution temperature increasing, and when the solution temperature was fixed, the ultimate tensile strength and the elongation of the Al-Si-Cu-Mg alloy treated by T6 increased at first and then decreased while the solution time increasing, but the hardness of the alloys affected less by the solution time.     

Cu/W-Ni-Co/Ni多中间层的钨/钢扩散连接

采用铜箔/90W-5Ni-5Co(质量分数,%)混合粉末/镍箔复合中间层,在加压5 MPa、连接温度1120℃、保温60 min的工艺条件下,对纯钨(W)和0Cr13Al钢进行了连接。利用SEM、EDS、电子万能试验机及水淬热震实验等手段研究了接头的微观组织、成分分布、断口特征、力学性能及抗热震性能。结果表明,连接接头由钨母材、Cu-Ni-Co合金层、钨基高密度合金层、镍层、钢母材5部分组成。接头中的钨基高密度合金层由90W-5Ni-5Co混合粉末固相烧结生成,其Ni-Co粘结相和钨颗粒相冶金结合且分布均匀。钨基高密度合金层与钨母材以瞬间液相扩散连接机制实现了良好结合。接头剪切强度达到286 MPa,断裂均发生在钨基高密度合金层/镍层结合区域,断口形貌呈现为韧性断裂。经过60次700℃至室温的水淬热震测试,接头无裂纹出现。