GRAIN REFINEMENT IN BULK UNDERCOOLED Ni-BASED ALLOY

Fluxing of 5 g bulk melt Ni77Si13B10 permits high undercoolings to be attained prior to nu-cleation onset.Investigations of grain refinement in the bulk undercooled alloy as a function ofundercooling,recalescence behavior and cooling rate have been reported.A significant inhomo-geneity of reduction in grain size of a bulk sample is observed,which is caused by the different so-lidification conditions:(1)recalescence process,and(2)the followed plateau in which the heatrelease and extraction rates are equal.It is concluded that the homogeneous refined microstructurecan be achieved if the initial undercooling prior to nucleation,or cooling rate after recalescence isfurther increased.     

BSTUDY ON Ni_(25)Ti_(50)Cu_(25) SHAPE MEMORY PARTICLE/Al MATRIX COMPOSITE

ＳＴＵＤＹＯＮＮｉ_（２５）Ｔｉ_（５０）Ｃｕ_（２５）ＳＨＡＰＥＭＥＭＯＲＹＰＡＲＴＩＣＬＥ／ＡｌＭＡＴＲＩＸＣＯＭＰＯＳＩＴＥＬ．Ｓ．Ｃｕｉ；Ｍ．Ｑｉ；Ｐ．Ｓｈｉ；Ｆ．Ｘ．ＣｈｅｎａｎｄＤ．Ｚ．Ｙａｎｇ（ＤｅｐａｒｔｍｅｎｔｏｆＭａｔｅｒｉａｌｓＥ?..     

深过冷Ni—50%Cu合金的晶粒细化

Ｎｉ－５０％Ｃｕ合金随过冷度的增加发生两次明显的晶粒细化过程,第一次产生于５０－１００Ｋ的过冷度范围内,第二次发生于临界过冷度２２０Ｋ之后,实验首次发现高冷度下细化合金的晶粒内含有枝晶亚结构。理论分析指出,枝晶重熔倾向的大小可用枝晶主干中最先析出的固相在再辉过程中的无量纲过热度来衡量,该无量钢过热度随原始过冷度的增加先增后减,其最大值对应于第一次细化发生的过冷度区间。热力学计算和组织分析表明,小过     

用非晶态合金作中间层对Si_3N_4陶瓷进行扩散焊连接

研制了两种非晶态物质Ｃｕ_（５０）Ｔｉ_（５０），Ｃｕ_（５０）Ｔｉ_（５０）Ｂ作为对Ｓｉ_３Ｎ_４扩散焊连接的中间层材料．研究结果表明：用非晶态作为中间层可改善工艺条件，降低扩散焊温度；非晶态中间层接头比其相应晶态中间层接头的剪切强度有明显提高．其中硼对提高接头剪切强度贡献很大．用非晶态Ｃｕ_（５０）Ｔｉ_（５０）Ｂ作中间层时，接头强度最高可达３４０ＭＰａ用晶态和非晶态Ｃｕ_（５０）Ｔｉ_（５０），Ｃｕ_（５０）Ｔｉ_（５０）Ｂ作中间层对Ｓｉ_３Ｎ_４进行扩散焊连接的机制是：活性元素Ｔｉ向陶瓷界面扩散和富集并与Ｓｉ_３Ｎ_４发生反应生成界面相ＴｉＮ，ＴｉＳｉ_２等．从而实现连接．     

Zr50Cu50合金过冷熔体中的晶体生长速度

利用静电悬浮设备成功地实现了Zr50Cu50合金熔体的深过冷与凝固,并测得了在近200K的过冷度范围内的晶体生长速度．随过冷度的增加,初生ZrCu相的晶体生长速度几乎呈线性增大,但在整个测量的过冷度范围之内,其生长速度极低,比一般的金属、Si和Ge等的生长速度低两个数量级以上．     

TC11钛合金棒材显微组织等轴细晶化工艺研究

本文对TC11钛合金棒材显微组织不均匀缺陷产生原因及消除途径进行了研究。结果表明,由于铸锭最初锻造温度在β相区,随后两相区锻造变形量不大且分布不均匀,致使部分晶界α和二次α聚集并粗化呈块状,或沿主变形方向拉长呈条状,或遗留下原晶界α。若采用(α+β)中间形变热处理+β处理、水冷+再结晶退火、空冷的工艺,可完全消除晶界α,拉长α和块状α相,获得均匀细小等轴α组织,初生等轴α相的平均直径可细化至1.9μm。     

过冷Ni50Cu50合金的二次枝晶间距

过冷Ｎｉ５０Ｃｕ５０合金的二次枝晶间距随过冷度的增加并不以简单的幂函数规律减小,在４０－１２０Ｋ过冷度范围内有一反常的变化,理论分析指出这是枝晶生长从低过冷下的溶质扩散控制向高过冷下的热扩散控制转变过程中一次枝晶尖端半径的上升所致。与常规凝固合金相比,深过冷合金的二次枝晶在凝固过程中发生剧烈的粗化。     

超声场作用下Al-Si合金的除气效果及晶粒细化

在不同的恒温条件下,对Al-Si合金熔体进行不同时间的超声处理,当超声处理时间为60 s时,试样含气量显著降低,除气效果明显.在Al-Si合金凝固过程中施加超声场,晶粒发生球化、细化现象;在Al-Si合金凝固区间恒温条件下施加超声场,晶粒发生细化但未发生球化现象.超声场作用下Al-Si合金晶粒细化主要是由于空化泡破碎产生的过冷生核所造成的.     

微重力条件下Pd40Ni40P20合金凝固组织中磷原子的分布

在中国返地卫星上研究了Ｐｄ（４０）Ｎｉ（４０）Ｐ（２０）合金凝固样品中磷原子的分布行为。发现与重力条件下凝固样品相比，微重力条件下样品凝固组织中初生相的含磷量较低，而共晶区域内的平均磷含量较高。另外，微重力条件下样品显微组织中共晶区域内具有Ｐｄ－Ｎｉ固溶体晶格类型的相的形态和溶质原子磷含量均发生了明显的变化。讨论了微重力及重力凝固条件下溶质原子的分配原则，并对合金凝固过程中溶质原子磷的分布行为进行了分析。     

EQUIAXED REFINEMENT OF GRAINS IN ALLOY TC11

The formation reason and elimination method of non-uniform microstructure defects in Ti al-loy TC11 bar have been studied.The coagulating and coarsening into block of the part ofgrain boundary α and secondary α seem to be caused by the ingot cogging and initial forgingtemperature in the β region as well as no more enough deformation and uneven distribution.The grain α,elongated α and blocky α may be finally eliminated by adopting the technique of(α+β)thermomechanical processing+β processing,W.Q.+recrystallization annealing,A.C.,thus the size of uniform and fine equiaxed α structure is believed to be reduced to 1.9258μm.     

SURFACE OXIDATION OF THE AMORPHOUS ALLOY Ni_(68)P_(18)Cr_(14)

The surface layer of Ni_(68)P_(18)Cr_(14) amorphous alloy was studied by AES and XPS associated with ion beam sputtering. It was found that great differences existed between the surface layer and the bulk both in composition and chemical states. The dominant component elements Ni and P were of lower content in the surface laver, while Cr was enriched. Cr was drastically oxidized in the surface layer, but Ni underwent no oxidation. There was a P enriched region just helow the surface oxide layer, which was supposed to enhance the surface segregation of Cr. Ni underwent no oxidation in Ni_(68)P_(18)Cr_(14) amorphous alloy.     

LOCAL STRUCTURE OF SUPERCOOLED LIQUID Ni_(80)P_(20) ALLOY

ＬＯＣＡＬＳＴＲＵＣＴＵＲＥＯＦＳＵＰＥＲＣＯＯＬＥＤＬＩＱＵＩＤＮｉ_（８０）Ｐ_（２０）ＡＬＬＯＹ￥ＣＨＥＮＫｕｉｙｉｎｇ;ＬＩＵＨｏｎｇｂｏ;ＨＵＺｈｕａｎｇｑｉ（ＳｔａｔｅＫｅｙＬａｂｏｆＲＳＡ,ＩｎｓｔｉｔｕｔｅｏｆＭｅｔａｌＲｅｓｅａｒｃｈ...     

QUASICRYSTALLINE AND CRYSTALLINE PHASES IN RAPIDLY SOLIDIFIED Al_（33）Cu_（10）Fe_（24）Ti_（33） ALLOY POWDERS

ＱＵＡＳＩＣＲＹＳＴＡＬＬＩＮＥＡＮＤＣＲＹＳＴＡＬＬＩＮＥＰＨＡＳＥＳＩＮＲＡＰＩＤＬＹＳＯＬＩＤＩＦＩＥＤＡｌ_（３３）Ｃｕ_（１０）Ｆｅ_（２４）Ｔｉ_（３３）ＡＬＬＯＹＰＯＷＤＥＲＳＷｕＬｉｊｕｎ；ＣｈｅｎＺｈｅｎｈｕａ；ＨｕＷａｎｇｙｕ；Ｈｕａ...     

Ni20Ti50C30机械合金化过程中的爆炸反应

机械合金化Ｎｉ２０Ｔｉ５０Ｃ３０粉末发生了爆炸式反应，反应产物中粉末和块状样品共存，经Ｘ射线衍射分析和扫描电镜观察表明反应过程中各存在部分熔化。产物组成主要为ＴｉＣ和Ｎｉ－Ｔｉ金属间化合物。作者认为球磨过程中球与球的猛烈撞击引发了初始ＴｉＣ的形成，其巨大的生成热诱发了后续反应。     

MOLECULAR STATIC SIMULATION OF ENERGY FEATURESOF INTERACTION BETWEEN GRAIN BOUNDARYAND DISLOCATIONS IN Ni＿3Al ALLOY

ＭＯＬＥＣＵＬＡＲＳＴＡＴＩＣＳＩＭＵＬＡＴＩＯＮＯＦＥＮＥＲＧＹＦＥＡＴＵＲＥＳＯＦＩＮＴＥＲＡＣＴＩＯＮＢＥＴＷＥＥＮＧＲＡＩＮＢＯＵＮＤＡＲＹＡＮＤＤＩＳＬＯＣＡＴＩＯＮＳＩＮＮｉ＿３ＡｌＡＬＬＯＹＣｈｅｎ，Ｄａ；Ｌｕ，Ｍｉｎ；Ｌｉｎ，Ｄｏｎｇ...     

ACTIVATION MECHANISM OF AMORPHOUS Ni_（63）Zr_（32）La_5 ALLOY HYDROGENATION CATALYST

ＡＣＴＩＶＡＴＩＯＮＭＥＣＨＡＮＩＳＭＯＦＡＭＯＲＰＨＯＵＳＮｉ_（６３）Ｚｒ_（３２）Ｌａ_５ＡＬＬＯＹＨＹＤＲＯＧＥＮＡＴＩＯＮＣＡＴＡＬＹＳＴ￥Ｘ．Ｋ．Ｗａｎｇ．Ｎ．Ｆ．ＳｈｅｎａｎｄＧ．ＪＬｅｉ（Ｄｅｐｔ．ｏｆＭａｔｅｒｉａｌｓＳｃｉｅｎｃｅａ?..     

深过冷Cu50Ni50熔体凝固的定向枝晶组织

在高真空度下,采用熔融玻璃净化与循环过热相结合的方法,在宽的过冷度范围内,研究了Ｃｕ５０Ｎｉ５０合金凝固组织开头演化过程。结果表明,随着过冷度增大,凝固组织发生了３次转变。其中,当１２０Ｋ（ΔＴ＾＊２）〈ΔＴ〈１９２Ｋ（ΔＴ＾＊３）时,凝固组织发生第２次转变,由粒状晶演变为定向生长的深过冷枝晶。通过组织观察和过冷熔体枝晶生长过程的计算发现,快速凝固形成的枝晶在再辉和再辉结束后枝晶熟化过程被高度抑制     

HEAT CAPACITIES OF Fe_（40）Ni_（40）B_（20） GLASSY ALLOY MEASURED BY ENTHALPY METHOD

ＨＥＡＴＣＡＰＡＣＩＴＩＥＳＯＦＦｅ_（４０）Ｎｉ_（４０）Ｂ_（２０）ＧＬＡＳＳＹＡＬＬＯＹＭＥＡＳＵＲＥＤＢＹＥＮＴＨＡＬＰＹＭＥＴＨＯＤ￥ＪＩＡＮＧＱｉｎｇ;ＺＨＡＯＭｉｎｇ;ＬＩＪｉａｎｃｈｅｎ（ＪｉｌｉｎＵｎｉｖｅｒｓｉｔｙｏｆＴｅｃｈｎｏｌ?..     

微量Sc和Zr对Al—Mg合金铸态组织的晶粒细化作用

制备了Ａｌ５Ｍｇ、Ａｌ５Ｍｇ０．２Ｓｃ、Ａｌ５Ｍｇ０．１Ｚｒ和Ａｌ５Ｍｇ０．２Ｓｃ０．１Ｚｒ四种铸态合金，采用金相显微镜和扫描电镜观察分析了微量Ｓｃ和Ｚｒ对ＡｌＭｇ合金铸态组织的晶粒细化作用及其机理。结果发现，０２％的Ｓｃ并未使ＡｌＭｇ合金产生晶粒细化作用，而０２％的Ｓｃ与０１％的Ｚｒ复合添加则使ＡｌＭｇ合金产生了极其强烈的晶粒细化作用。这一作用的产生，是由于Ｓｃ、Ｚｒ与Ａｌ在合金熔体中生成了Ａｌ３Ｓｃ和Ａｌ３Ｚｒ复合粒子，这种粒子在合金凝固过程中，起到了非均质晶核细化晶粒的作用     

A Zr-RICH LOW MELTING POINT PHASE IN Ni_3Al ALLOY WITH Zr

A Zr-rich phase,Ni_5Zr,with low melting point has been fouhd in an Ni_3Al alloy doped withZr(1.2at.-%).It will cause the incipient melt of the alloy after being homogenized at 1300℃.This makes it difficult to homogenize the coarse casting structures completely and limits thefurther improvement of properties of the Ni_3Al alloy.