新一代飞机发动机用Nb基超高温材料设计系统开发

本研究利用CALPHAD方法,液相和端际固溶体相的自由能采用亚规则溶体模型来描述,金属间化合物相的自由能用亚点阵模型来描述,并结合相平衡实验结果和热力学性质的实验信息,对Nb-Al-Cr-Hf-Mo-Si-Ti体系合金相图进行了热力学优化与计算.计算结果与实验值取得了较好的一致性,得到一组自洽合理的热力学参数.本研究结合该体系相关合金相图热力学计算的文献报道,建立了Nb-Al-Cr-Hf-Mo-Si-Ti体系合金相图热力学数据库.该热力学数据库将为铌基高温合金材料研究与开发提供重要的基础热力学参数.     

新一代飞机发动机用Nb基超高温材料设计系统开发EI

本研究利用CALPHAD方法,液相和端际固溶体相的自由能采用亚规则溶体模型来描述,金属间化合物相的自由能用亚点阵模型来描述,并结合相平衡实验结果和热力学性质的实验信息,对Nb-Al-Cr-Hf-Mo-Si-Ti体系合金相图进行了热力学优化与计算.计算结果与实验值取得了较好的一致性,得到一组自洽合理的热力学参数.本研究结合该体系相关合金相图热力学计算的文献报道,建立了Nb-Al-Cr-Hf-Mo-Si-Ti体系合金相图热力学数据库.该热力学数据库将为铌基高温合金材料研究与开发提供重要的基础热力学参数.     

Au-Pt-Sn体系热力学参数及相图研究现状与展望

较为系统地介绍了Au-Pt-Sn系中二元及三元合金的相图及相关热力学参数研究进展,包括相图分析、合金相结构以及生成焓、结合能、吉布斯自由能等热力学参数,同时介绍了该系合金体系在钎焊和化学催化产业中的应用,并提出了扩大该系合金应用值得重视的一些问题。     

Au-Pt-Sn体系相图及相关热力学参数的研究进展

较为系统地介绍了Au-Pt-Sn系中二元及三元合金的相图及相关热力学参数的研究进展,包括相图分析、合金相结构以及生成焓、结合能、吉布斯自由能等热力学参数,同时介绍了该系合金体系在钎焊和化学催化产业中的应用,并提出了扩大该系合金应用值得重视的一些问题。     

多组元合金的凝固热力学原理

以发展多元多相合金的凝固理论为目标，探讨了多组元合金自由能描述方法及其凝固过程的热力学平衡条件。多组元合金的自由能是由各组成元素的自由能、原子的组合排列引起熵的变化决定的理想混合自由能和由原子间交互作用引起的附加自由能三部分决定的。其中附加自由能的描述是难点，通常通过实验结果的拟合获得。固相的析出条件可通过自由能最低的热力学原理预测，而固相和液相成分的相关性则可通过化学位相等的热力学原理计算。在实际应用中，可以借鉴相图计算方法进行凝固过程的热力学分析，进而获得相图精细结构的数值计算结果。以Al Mg Si合金为算例，进行了三元合金热力学平衡条件的分析。以该热力学平衡条件计算结果为基础，引入对固相和液相中扩散过程的分析，则可实现多组元合金凝固路径的预测。     

Ca-La2O3-Ni体系的热力学研究

计算了用Ca还原La2O3生成纯金属La(3Ca La2O3=2La 3CaO),La与Ni反应生成LaNi5合金（La 5Ni=LaNi5)的标准吉布斯自由能和吉布斯自由能变化,以及反应平衡时的钙分压,在1223,1273,1323,1373K温度下制得了LaNi5合金,XRD鉴定了反应产物的物相,热力学计算说明在La-NI系化合物中生成物只能是L aNi5。     

气体吸附诱导Cu(Au)合金中Au原子的偏聚和富集

合金中的表面成分和相偏析会改变其功能,尤其是在表面结构和化学起着至关重要作用的应用中.例如,合金催化剂的表面状态显著影响其在异相催化和电化学过程中的催化性能.表面成分偏析被认为是由表面能的差异驱动,以减少合金体系的总自由能.然而,目前合金中成分偏析的原子尺度进程还尚不清楚,尤其是对于气体分子诱导的成分偏析,在该过程中可能同时发生结构和化学重排.本文通过像差校正环境TEM从原子尺度研究了固溶态Cu(Au)合金在CO气氛下的表面偏析行为. CO气氛能够诱导Cu(Au)合金表面形成有序结构,在很大程度上改变合金的表面化学性质.高温条件下, CO气氛会进一步促进Au原子通过特定的"原子通道"进行扩散,在合金表面偏聚和富集.富集形成的Au纳米颗粒与合金表面在形貌和结构方面发生了丰富的动力学交互作用.这其中CO气体吸附也起着重要的作用.这些原子尺度的研究结果为双金属合金的表面偏析和去合金化机理提供了直接证据,并突出了气体吸附物在这些表面行为中的作用.     

SrTi_xZr_(1-x)O_3固溶体的合成及其热力学分析

以硝酸锶、氧氯化锆、四氯化钛和氢氧化钠为原料,采用直接沉淀法一步合成了SrTi_xZr_(1-x)O_3(x＞0.4)连续固溶体粉体,陈化处理x＜0.4的沉淀产物后,也可获得相应组成的结晶粉体.根据热力学原理,根据建立的计算模型,计算了生成SrTi_xZr_(1-x)O_3及其相关反应物的Gibbs生成自由能,从计算结果分析并解释了直接沉淀法合成SrTi_xZr_(1-x)O_3连续固溶体组成中的x取此范围.     

GH586高温合金析出相的热力学模拟计算

利用热力学计算软件Thermo—Calc与相应的Ni基高温合金数据库，从热力学角度通过计算最小吉布斯自由能，得到GH586合金可能析出的平衡相，并预测化学成分对析出相的影响，分析各相的析出规律，为挖掘合金组织潜力和改善合金使用性能提供理论依据。     

计算材料热力学与镁合金设计

计算材料学经过近30年的发展,已形成针对材料不同层次和尺度的理论模型,包括第一性原理计算、分子动力学、蒙特卡洛模拟、相场理论、CALPHAD技术及有限元分析等。其中计算材料热力学在多层次跨尺度材料设计中占据重要的地位。通过计算材料热力学获得的多元合金体系的相关系、相组成和相对量、相转变驱动力及其它热化学数据等基础性研究成果,将直接服务于相关材料的设计与研发。简要介绍了计算材料热力学的发展历程及其基本原理,结合Mg基合金设计过程,基于建立的部分Mg合金体系的热力学数据库,从固溶强化、时效强化、析出强化、晶粒细化、非晶形成能力等方面,对Mg合金体系的热力学评估方法和研究现状进行了概述,并根据Mg合金热力学数据库中关于Mg-Zn-Zr/Ca体系的热力学特征函数,计算相平衡关系,示例分析了Mg-Zn合金中Zr和Ca的合金化作用。     

铁电（Pb_（0．925）La_（0．075））（Zr_（0．65）Ti_（0

本文对射频磁控溅射制备的（Ｐｂ＿（０．９２５）Ｌａ＿（０．０７５）－（Ｚｒ＿（０．６５）Ｔｉ＿（０．３５））＿（０．９８１）Ｏ＿３薄膜作了ＸＰＳ全扫描和窄扫描能谱分析。结果表明，薄膜的表面缺Ｐｂ是形成ＴＺＯ相的主要原因；随着退火温度的升高，薄膜中钙钛矿相的形成导致各元素的结合能发生位移。     

(Pb_(0.5)Sr_(0.5))TiO_3薄膜的表面化学态研究

用溶胶-凝胶法制备(Pb_(0.5)Sr_(0.5))TiO_3(简称PST)前驱体溶液,以三水醋酸铅、醋酸锶、钛酸丁酯为原料,乙二醇甲醚、去离子水、乙酰丙酮做溶剂,通过旋涂工艺在Pt/Ti/SiO_2/Si(100)基片上沉积PST薄膜.薄膜经320～380℃热分解,再经650℃退火30min,得到晶化好的薄膜样品,X射线衍射结果表明PST薄膜为钙钛矿立方相结构,其晶格常数为a=0.3919nm.用原子力显微镜观测其表面形貌,薄膜平均晶粒尺寸为300nm.用XPS测量了650℃退火PST薄膜样品的表面化学态,结果表明表面富铅,接近表面区域的原子比率Pb∶Sr∶Ti∶O是0.52∶0.50∶1.0∶3.02,接近(Pb_(0.5)Sr_(0.5))TiO_3的理想配比.     

机械合金化能量转换与Ni_(50)Ti_(50)非晶合金的形成

本文报道了球磨转速,装球量对 Ni_(50)Ti_(50)单质混合粉机械合金化的影响,并建立模型用于计算工艺条件对球磨能量转换的影响,进而讨论了它与机械合金化相变反应方式的关系。粉末在每次碰撞的变形能过高时,可能形成金属间化合物,而粉末经长时间球磨获得的总能量超过一定值将引起非晶的晶化。     

Thermal Stability of Amorphous Hydride Mg_(50)Ni_(50)H_(54) and Mg_(30)Ni_(70)H_(45)

The thermal stability of amorphous ternary hydrides Mg_(50)Ni_(50)H_(54) and Mg_(30)Ni_(70)H_(45) and their corre-sponding amorphous binary alloys Mg_(50)Ni_(50) and Mg_(30)Ni_(70) were studied with X-ray diffraction(XRD) and differential scanning calorimetry(DSC). Samples of the amorphous alloys were preparedby mechanical alloying and the amorphous hydrides were obtained by charging the alloys with gas-eous hydrogen at 3.0 MPa and 423 K. It was found that the amorphous hydrides released most oftheir hydrogen before the crystallization of the essentially hydrogen depleted amorphous alloy. Thecrystallization temperature of amorphous Mg_(50)Ni_(50)H_(54) elevated and that of amorphousMg_(30)Ni_(70)H_(45) did not change in relation to the original binary amorphous alloy. This is very excep-tional for amorphous hydrides. The reason for the effects of hydrogen absorption/desorption on thecrystallization of amorphous alloys was discussed.     

机械合金化Fe50Ti50非晶的形成及球磨强度对它的影响

本文通过电子扫描和Ｘ衍射对机械合金人Ｆｅ５０Ｔｉ５０非晶粉末形成做了研究。研究发现：机械合金非晶形成可以大致地分为二个阶段－粉末的破碎阶段和非晶的形成阶段。另外，对球磨强度对非晶形成的影响进行了研究。结果表明：强度低时粉末需要较长的时间才能形成非晶，强度高时粉末形成非晶的时间大大缩短，但在随后的球磨中，粉末会重新晶化形成新相。     

Microstructure of the Ductile Phase in Intermetallic Compound Ni_(50)Al_(20)Fe_(30)

The microstructure of the single hot extruded and annealed Ni50Al20Fe30Y0.003 intermetallic compound alloys has been examined by means of high resolution electron microscopy (HREM). In these extruded and annealed alloys. the ductile phase is of a mixture of the disordered fcc γ matrix and or dered γ' precipitates. This fact well interprets the reason why the degree of annealing treatment can influence the strength and ductility of these alloys. The HREM observation revealed directly that there was some strain concentration at γ'-γ interfaces, due to the presence of more iron atoms in these two phases. The fixed orientation relationship between the γ phase and γ' precipitates was identified to be {001}γ{00 }γ' and <100 >γ < 100 > γ'     

Geometrical imperfection and adiabatic shear banding

This work addresses the effect of small geometrical imperfections on adiabatic shear band (ASB) formation. The separate effect of the length and radius of short notches is systematically investigated in AM50 and Ti6Al4V alloys, using shear compression specimens. It is observed that the length of the imperfection does not influence ASB formation in these experiments. By contrast, the notch-root radius appears to be the dominant parameter for the two materials, in perfect agreement with the analytical predictions of Dinzart et al. [The catastrophic development of shear localization in thermoviscoplastic materials. J Phys 1994; IV(C8): 435–40]. The distribution of deformation energy over the gauge length is modeled numerically. The calculated average dynamic deformation energy levels are quite similar to those that are measured for the two investigated alloys. It is concluded that the global measure of the dynamic deformation energy provides valuable information about ASB failure from geometrical imperfections.     

含ADN或TKX-50的叠氮高能固体推进剂能量特性分析

利用最小自由能法研究了叠氮类［如聚叠氮缩水甘油醚(GAP)、3,3’-双叠氮甲基氧丁烷-四氢呋喃共聚醚(PBT)、聚3-甲基-3-叠氮甲基环氧丁烷(PAMMO）］高能固体推进剂的能量特性参数,重点研究了二硝酰胺铵(ADN)和5,5’-联四唑-1,1’-二氧二羟铵(TKX-50)在不同固体填料配比下对推进剂能量特性的影响规律。结果表明:在高固含量的叠氮推进剂中,用ADN取代高氯酸铵(AP),由于燃烧产物平均相对分子量降低,推进剂比冲提高;叠氮类推进剂能量由大到小为GAP、PBT、PAMMO;TKX-50用于叠氮类高能固体推进剂中,由于体系内的负氧平衡问题,TKX-50与奥克托今(HMX)、AP或ADN间存在能量的最优配比。用TKX-50完全取代HMX时,ADN/TKX-50/Al推进剂的理论比冲为2 790.6 N?s/kg,比ADN/HMX/Al推进剂的理论比冲增加了30.7 N?s/kg。     

Structure, mechanical metallurgy and electrical transport properties of rapidly solidified Pb50Sn50-xBix alloys

Electrical transport properties, structure and mechanical properties of Pb₅₀Sn_50-xBi_x(0≤x≤50) alloys have been studied and analyzed. The addition of bismuth in the amounts of 30 wt % and 50 wt % results in the appearance of the crystalline metastable χ(Pb-Bi) phase. Y phase is also identified and it is found at 50 wt % bismuth. Electrical transport is sensitive to the alloys composition, decreasing as the bismuth content increases. The Vickers hardness number is sensitive to the structure of the quenched ribbons. The lowest value of H_v is 55 MPa for the Pb₅₀Sn₂₀Bi₃₀ alloy, which is attributed to the formation of the metastable χ(Pb-Bi) after a rapid quench from the melt. Values of the equivalent Fermi temperature, T_F Fermi velocity, V_F and the Fermi wave vector, K_F , are also computed. © 2000 Kluwer Academic Publishers     

The effects of ruthenium additions on tensile deformation mechanisms of single crystal superalloys at different temperatures

The tensile behavior of two experimental nickel-base single crystal superalloys has been studied from room temperature to 1100 °C. Emphasis is placed on elucidating the effects of ruthenium (Ru) additions on the deformation mechanisms using transmission electron microscopy (TEM). Furthermore, the partitioning behavior of the alloy elements between the γ and γ′ phases for both experimental alloys has been studied using three-dimensional atom probe (3DAP). Detailed analysis demonstrates that at low and medium temperature ranges, the stacking faults present in the γ matrix of the 3Ru alloy but no trace of stacking fault in the γ matrix of the 0Ru alloy have been observed; during high temperature range, as a result of Ru additions, the γ/γ′ interfacial dislocation space of the 3Ru alloy is smaller than that of the 0Ru alloy due to further decreasing the lattice misfit. Apart from that, Ru additions result in more Re partitioning to the γ′ phase, and thus the solution strengthening for the γ phase is decreasing. Thus, during tests below and at the temperature corresponding to the peak strength, the yield strength of the 3Ru alloy is lower than that of the 0Ru alloy. At last, in the light of the TEM observations, the changing trends of the stacking fault energy in the γ matrix and the transformation points (the temperature related to the stacking faults formation) for the two experimental alloys have been drawn. The temperature range of the stacking faults formation in the γ matrix is expanded after Ru additions. The energy conditions of the stacking faults formation of the 0Ru and 3Ru alloys have been analyzed in detail. The changing of lattice misfit with temperature can be considered as one of the principal reasons for the stacking faults formation.