APPLICABILITY OF QUASICHEMICAL MODEL FOR SOME LIQUID ALLOYS WITH STRONG-INTERACTED COMPONENTS

ＡＰＰＬＩＣＡＢＩＬＩＴＹＯＦＱＵＡＳＩＣＨＥＭＩＣＡＬＭＯＤＥＬＦＯＲＳＯＭＥＬＩＱＵＩＤＡＬＬＯＹＳＷＩＴＨＳＴＲＯＮＧＩＮＴＥＲＡＣＴＥＤＣＯＭＰＯＮＥＮＴＳ①ＬｉＪｉａｎｆｅｎｇ，ＤｅｎｇＨｏｎｇｍｅｉ，ＣｈｅｎＮｉａｎｙｉＳｈａｎｇｈａｉ...     

DESIGN AND PREPARATION OF SILICON NITRIDE COMPOSITE WITH HIGH FRACTURE TOUGHNESS AND NACRE STRUCTURE

ＤＥＳＩＧＮＡＮＤＰＲＥＰＡＲＡＴＩＯＮＯＦＳＩＬＩＣＯＮＮＩＴＲＩＤＥＣＯＭＰＯＳＩＴＥＷＩＴＨＨＩＧＨＦＲＡＣＴＵＲＥＴＯＵＧＨＮＥＳＳＡＮＤＮＡＣＲＥＳＴＲＵＣＴＵＲＥＹＨｕａｎｇ；Ｈ．ＮＨａｏ；Ｙ．Ｌ．ＣｈｅｎａｎｄＢ．Ｌ．Ｚｈｏｕ（１）Ｄｅ...     

EFFECT OF TRACE ELEMENTS WITH ZERO SELF－INTERACTIONCOEFFICIENT ON CRYSTALLIZATION TEMPERATUREOF IRON CARBON ALLOYS

ＥＦＦＥＣＴＯＦＴＲＡＣＥＥＬＥＭＥＮＴＳＷＩＴＨＺＥＲＯＳＥＬＦ－ＩＮＴＥＲＡＣＴＩＯＮＣＯＥＦＦＩＣＩＥＮＴＯＮＣＲＹＳＴＡＬＬＩＺＡＴＩＯＮＴＥＭＰＥＲＡＴＵＲＥＯＦＩＲＯＮＣＡＲＢＯＮＡＬＬＯＹＳＺＨＡＩＱｉｊｉｅａｎｄＨＵＨａｎｑｉ（Ｄｅｐ...     

MICROSTRUCTURE，INTERFACE AND MECHANICAL PROPERTIES OF NiAl－BASED COMPOSITES REINFORCED BY TiB_2 PARTICULATES

ＭＩＣＲＯＳＴＲＵＣＴＵＲＥ，ＩＮＴＥＲＦＡＣＥＡＮＤＭＥＣＨＡＮＩＣＡＬＰＲＯＰＥＲＴＩＥＳＯＦＮｉＡｌ－ＢＡＳＥＤＣＯＭＰＯＳＩＴＥＳＲＥＩＮＦＯＲＣＥＤＢＹＴｉＢ_２ＰＡＲＴＩＣＵＬＡＴＥＳＧＵＯＪｉａｎｔｉｎｇ（ＩｎｓｔｉｔｕｔｅｏｆＭｅｔａ?..     

CRYSTAL STRUCTURE OF A LONG－PERIOD ORDERED PHASE IN Fe－C MARTENSITE AND COMPUTER SIMULATION OF ITS ELECTRON DIFFRACTION PATTERNS

ＣＲＹＳＴＡＬＳＴＲＵＣＴＵＲＥＯＦＡＬＯＮＧ－ＰＥＲＩＯＤＯＲＤＥＲＥＤＰＨＡＳＥＩＮＦｅ－ＣＭＡＲＴＥＮＳＩＴＥＡＮＤＣＯＭＰＵＴＥＲＳＩＭＵＬＡＴＩＯＮＯＦＩＴＳＥＬＥＣＴＲＯＮＤＩＦＦＲＡＣＴＩＯＮＰＡＴＴＥＲＮＳＲＥＮＸｉａｏｂｉｎｇ；ＷＡ...     

EFFECT OF MILLING INTENSITY ON STRUCTURAL CHANGES OF MIXED Al－Fe－Ni POWDERS IN MECHANICAL ALLOYING PROCESS

ＥＦＦＥＣＴＯＦＭＩＬＬＩＮＧＩＮＴＥＮＳＩＴＹＯＮＳＴＲＵＣＴＵＲＡＬＣＨＡＮＧＥＳＯＦＭＩＸＥＤＡｌ－Ｆｅ－ＮｉＰＯＷＤＥＲＳＩＮＭＥＣＨＡＮＩＣＡＬＡＬＬＯＹＩＮＧＰＲＯＣＥＳＳ￥ＬｉｕＺｕｙａｎ；ＬｉａｎｇＧｕｏｘｉａｎ；ＷａｎｇＥｒｄｅ（Ｓ...     

A NEW ORTHOTROPIC YIELD FUNCTION DESCRIBABLE ANOMALOUS BEHAVIOR OF MATERIALS

ＡＮＥＷＯＲＴＨＯＴＲＯＰＩＣＹＩＥＬＤＦＵＮＣＴＩＯＮＤＥＳＣＲＩＢＡＢＬＥＡＮＯＭＡＬＯＵＳＢＥＨＡＶＩＯＲＯＦＭＡＴＥＲＩＡＬＳＡＮＥＷＯＲＴＨＯＴＲＯＰＩＣＹＩＥＬＤＦＵＮＣＴＩＯＮＤＥＳＣＲＩＢＡＢＬＥＡＮＯＭＡＬＯＵＳＢＥＨＡＶＩＯＲＯＦ...     

KINETICS OF LEACHING SPHALERITE WITH PYROLUSITE SIMULTANEOUSLY BY MICROWAVE IRRADIATION

ＫＩＮＥＴＩＣＳＯＦＬＥＡＣＨＩＮＧＳＰＨＡＬＥＲＩＴＥＷＩＴＨＰＹＲＯＬＵＳＩＴＥＳＩＭＵＬＴＡＮＥＯＵＳＬＹＢＹＭＩＣＲＯＷＡＶＥＩＲＲＡＤＩＡＴＩＯＮ①ＰｅｎｇＪｉｎｈｕｉ，ＬｉｕＣｈｕｎｐｅｎｇＤｅｐａｒｔｍｅｎｔｏｆＭｅｔａｌｕｒｇｙ，Ｋｕ...     

NUMERICAL PREDICTION OF PULSATING FLOW IN A LIQUID LINE WITH BRANCH OF HYDRAULIC SERVO SYSTEM

ＮＵＭＥＲＩＣＡＬＰＲＥＤＩＣＴＩＯＮＯＦＰＵＬＳＡＴＩＮＧＦＬＯＷＩＮＡＬＩＱＵＩＤＬＩＮＥＷＩＴＨＢＲＡＮＣＨＯＦＨＹＤＲＡＵＬＩＣＳＥＲＶＯＳＹＳＴＥＭ①ＨｅＹｏｎｇｓｅｎａｎｄＬｉｕＳｈａｏｙｉｎｇＣｈａｎｇｓｈａＩｎｓｔｉｔｕｔｅｏｆＭｉｎ...     

MICROSTRUCTURES AND PROPERTIES OF MOLYBDENUM WIRE DOPED WITH LANTHANUM OXIDE

ＭＩＣＲＯＳＴＲＵＣＴＵＲＥＳＡＮＤＰＲＯＰＥＲＴＩＥＳＯＦＭＯＬＹＢＤＥＮＵＭＷＩＲＥＤＯＰＥＤＷＩＴＨＬＡＮＴＨＡＮＵＭＯＸＩＤＥＭＩＣＲＯＳＴＲＵＣＴＵＲＥＳＡＮＤＰＲＯＰＥＲＴＩＥＳＯＦＭＯＬＹＢＤＥＮＵＭＷＩＲＥＤＯＰＥＤＷＩＴＨＬＡＮＴＨ...     

Simulation of the Influence of Pulsed Magnetic Field on the Superalloy Melt with the Solid-Liquid Interface in Directional Solidification

The effect of the pulsed magnetic field on the grain refinement of superalloy K4169 has been studied in directional solidification. In the presence of the solid-liquid interface condition, the distributions of the electromagnetic force, flow field, temperature field, and Joule heat in front of the solid-liquid interface in directional solidification with the pulsed magnetic field are simulated. The calculation results show that the largest electromagnetic force in the melt appears near the solid-liquid interface, and the electromagnetic force is distributed in a gradient. There are intensive electromagnetic vibrations in front of the solid-liquid interface. The forced melt convection is mainly concentrated in front of the solid-liquid interface, accompanied by a larger flow velocity. The simulation results indicate that the grain refinement is attributed to that the electromagnetic vibration and forced convection increase the nucleation rate and the probability of dendrite fragments survival, for making dendrite easily fragmented, homogenizing the melt temperature, and increasing the undercooling in front of the solid-liquid interface.     

EFFECT OF MELT SUPERHEAT ON DIRECTIONAL SOLIDIFICATION PROPERTIES OF Al-Cu ALLOY

本文研究了熔液过热对溶质分配系数及对定向凝固过程中界面形态临界条件的影响。 研究发现,实际溶质分配系数是液体状态的函数。提高熔液过热度导致实际溶质分配系数的增大(K_o<<的元素),并减小固-液界面形态稳定的临界比值(G/R),从而有利于定向凝固的进行。     

有外加相存在时Al-Si合金枝晶微观组织的数值模拟

对有外加SiC颗粒(SiCp)的Al-7.0%Si(质量分数)合金熔体凝固过程中球状颗粒与枝晶间相互作用,以及包含颗粒分布的微观组织形成过程进行了模拟研究.在热、溶质守恒的基础上考虑了溶质再分布、界面曲率以及各向异性的影响,并分别对颗粒、固相、液相以及固/液界面进行处理.建立了单个及多个颗粒与枝晶相互作用的数值模型,预测了单个颗粒与凝固界面之间的吞并/推移现象,并研究了颗粒附近枝晶生长的溶质浓度场、速度场以及界面形状,再现了多颗粒与多枝晶相互作用直至最终偏聚到枝晶间的过程.模拟结果表明:颗粒被推移时颗粒与界面的相互作用是一个非稳态的过程,但是在凝固速率较低的条件下可以按照稳态推移的模式进行处理.模拟得到的颗粒分布及微观组织与实验结果吻合较好.     

SOLIDIFICATION MECHANISM OF Al/TiC INTRAGRANULAR COMPOSITES FABRICATED BY CONTACT REACTION METHOD

The behaviour of the particles in solidification inter face front was studies,and the equctionof the critical inter face velocity which related to the supercooling and the volune fraction of particles in the melt was obtained.By the mean time,the two solidi fication mechanisms ofaluminium matrix intragranular composites was put forward.     

坩埚旋转波形参数对晶体组分偏析影响的数值研究

计算模拟了加速坩埚旋转技术Bridgman(ACRT-B)法生长Cd0．96Zn0.04Te单晶体过程，研究了ACRT波形参数对固-液界面凹陷和晶体内组分偏析的影响．计算结果表明：ACRT波形参数的变化几乎不影响固-液界面前沿熔体中均一浓度场的形成．但是，波形参数能够显著改变固-液界面的凹陷和晶体内的组分偏析．波形参数不适当时，固-液界面的凹陷深度增加数倍，同时晶体组分的径向偏析也显著增加．波形参数不适当时，固-液界面的凹陷深度不增加或增加很少，晶体组分的径向偏析显著减小，直至为零．本工作所选择的各种波形参数下，ACRT均能明显增加晶体组分的轴向偏析。     

利用Marangoni对流制备均质偏晶合金

利用温度场下第二相液滴的Ｍａｒａｎｇｏｎｉ运动，设计了一种在地球重力场下制备均质偏晶合金的“控制铸造”新技术。在这种技术中，偏晶合金凝固界面前沿的第二相液滴将在重力场下作Ｓｔｏｋｅｓ运动和在温度梯度场下作与重力方向相反的Ｍａｒａｎｇｏｂｎｉ运动。     

连续凝固偏晶合金薄带凝固组织进化过程模拟

分析了偏晶合金薄带垂直连续凝固过程,发展了描述该条件下偏晶合金凝固组织演变的数学模型,将计算的温度场和浓度场与凝固组织演变的控制方程相耦合,模拟了Al-5Pb(质量分数．%)合金的凝固过程．结果表明．在固/液界面前存在一过冷区、弥散相液滴在此区间内形核,这些液滴在移向凝固界面的过程中进行扩散长大,随着凝固速度的提高,形核率升高,弥散相液滴的数量密度增大．平均半径减小。     

二元合金激光快速熔凝过程的非Fourier模型

基于非Fourier定律，建立了脉冲激光加热条件下单相二元合金表面快速重熔和凝固过程的非平衡传热传质模型，并根据碰撞理论和Aziz的连续生长模型处理固／液界面，以解释快速熔凝过程界面动力学的非平衡效应，快速熔凝问题是涉及热质传输的移动界面问题，通过二阶精度的Von Neumann隐式差分格式和界面跟踪方法进行过程模型的数值求解。应用该模型，分析了Al-Cu二元合金的激光表面熔凝过程，结果表明，激光的高能量密度和非平衡界面动力学所引起的熔化过程和凝固过冷对于快速熔凝过程的影响很大，在快速熔凝过程中，界面速度的变化很大，且因基底材料和热流大小而不同，通过计算获得了界面温度，速度、溶质浓度及非平衡分配系数随界面位置的变化，结果显示，在凝固过程中界面速度和界面溶质浓度都存在着很大的波动。     

In-situ observation of porosity formation during directional solidification of Al-Si casting alloys

In-situ observation of porosity formation during directional solidification of two Al-Si alloys (7%Si and 13%Si) was made by using of micro-focus X-ray imaging.In both alloys,small spherical pores initially form in the melt far away from the eutectic solid-liquid (S/L) interface and then grow and coagulate during solidification.Some pores can float and escape from the solidifying melt front at a relatively high velocity.At the end of solidification,the remaining pores maintain spherical morphology in the ne...     

铝基复合材料中颗粒在凝固界面的行为

利用区域熔化定向凝固的方法,研究了Ａｌ／Ａｌ２Ｏ３及Ａｌ－Ｓｉ／Ａｌ２Ｏ３中颗粒在凝固界面的行为,通过在Ａｌ－Ｓｉ／Ａｌ２Ｏ３中添加微量元素,实现了颗粒被描捉并在固相中均匀分布的状态,提出了基于界面能的解释模型。