陶瓷超塑性的研究进展

本文综述了氧化锆及其复相陶瓷超塑性的研究现状，论述了陶瓷超塑性的变形机理，微观特征和断裂特性。同时，分析和对比了陶瓷超塑性与金属超塑性的特点。目前，对于正确理解超塑性陶瓷的变形机理，还需进行大量工作。     

陶瓷材料超塑性研究进展

超塑性是细晶陶瓷在高温下的固有属性。本文综述了陶瓷材料超塑性的一般特征和氧化钇稳定四方相氧化锆多晶陶瓷(Y-TZP)的形变机理及最新研究进展。解释了不同纯度Y-TZP陶瓷在Ⅰ区存在巨大差异的原因以及杂质特征对应力指数的影响。从能量的观点进一步分析了陶瓷材料超塑变形过程中的控速机制。对共价键陶瓷Si₃N₄、SiC的超塑性特征以及晶间玻璃相在超塑变形中的作用进行了概括。此外,还总结了其它陶瓷材料,包括Al₂O₃及其复合陶瓷、纳米陶瓷的研究进展及发展方向。     

陶瓷材料的超塑性

虽然陶瓷材料在本质上是一种脆性材料；然而研究已表明细晶陶瓷材料具有超塑性，在高温下能产生很大的拉伸形变．本文综述了超塑性的特征和Y2O3稳定四方ZrO2多晶体这种典型的超塑性陶瓷材料的形变机理，形变特征以及动态晶粒生长、玻璃相和产生孔穴对其超塑性形变的影响，此外，还总结了其他陶瓷材料，包括Al2O3、Al2O3－Y2O3稳定四方ZrO2、纳米陶瓷和玻璃陶瓷的超塑性行为和特征．     

陶瓷和金属间化合物的超塑性

本文介绍了陶瓷和金属间化合物超塑性的类型、特征、变形机制及其应用。     

陶瓷和金属间化合物的超塑性

本文介绍了陶瓷和金属间化合物超塑性的类型、特征、变形机制及其应用。     

铝合金超塑变形研究进展

综述了铝合金材料超塑变形的研究现状和进展情况.着重介绍了高应变速率下铝合金超塑性的基本特征,探讨了铝合金超塑变形机理,介绍了铝合金超塑性的应用情况.超塑铝合金是性能优良,具有广泛用途的新型材料,随着高应变速率条件下铝合金超塑变形研究的深入,将不断提高铝合金生产的经济效益和实用性.     

铝基复合材料高应变速率及低温超塑性的研究进展

综述了低温与高应变速率铝基复合材料超塑性的变形机理、制备工艺以及工业应用的研究现状和最新研究成果,并在目前已有研究的基础上展望了超塑性铝基复合材料的广阔应用前景。     

LF6铝合金的超塑性／扩散连接组合工艺试验及理论研究EI

本文研究了ＬＦ６铝合金的超塑性／扩散连接组合工艺，用变形和再结晶的方法细化晶粒，成功地进行了ＳＰＦ／ＤＢ工艺试验，利用电子探针观察了扩散连接接头的界面微观区域，并从机理上分析了金属的超塑性／扩散连接两种工艺之间的内部联系及其金属学行为。     

超塑性合金

所谓超塑性是指某种金属或陶瓷，在高温低应力拉伸变形时呈现出异常高的延伸率的一种现象。将这一现象应用于实际便可形成一种低成本省能源的零部件制造方法。超塑性具有下列特征：对于通常不可能进行塑性加工的难加工材料，如果能使晶粒细化就能显示其超塑性；可按接近所需形状和尺寸进行成形；成形之后的切削加工很少。因此，研究人员努力开发这种对众多难以近净成形的高强度材料和新型材料进行塑性加工的方法。     

Y－TZP陶瓷超塑性国内外研究进展EI

细晶Ｙ－ＴＺＰ陶瓷近年来已经显示出具有超塑性，这个发现引起了广泛的注意。国内研究发现Ｙ－ＴＺＰ在１７２３Ｋ时具有２４０％的延伸率。日本、美国等对Ｙ－ＴＺＰ超塑性进行了广泛的研究。虽然陶瓷超塑性在某些方面与金属超塑性相似，但也有许多重要的相异点，如晶粒尺寸、流动应力与应变速率对应关系和应力指数变化。     

Superplastic microstructures

Abstract

The production of fine, stable equiaxed grains, having disordered high angle boundaries, is a prerequisite for superplastic behaviour in crystalline solids. The way that superplastic microstructures can be achieved in pseudo-single-phase and duplex materials by thermomechanical processing is discussed for a number of commercially significant materials. The resulting superplastic deformation characteristics are outlined, as are the factors that influence cavitation during superplastic flow. Alloys based on aluminium, titanium, copper, iron, and nickel are considered, and also aluminium based metal-matrix composites, intermetallic phases, and crystalline ceramic materials. Recent work on markedly enhanced superplastic behaviour in aluminium and copper alloys and in stainless steels is reported, and the similarities between superplasticity in crystalline ceramics and metallic materials is discussed. The development of superplastic microstructures in metal-matrix composites, intermetallic phases, and ceramics has enhanced their formability and their potential as high temperature structural materials.

MST/1298     

陶瓷材料超塑性的研究进展与应用前景

综述了陶瓷材料超塑性的研究进展和应用前景，介绍了超塑性成型，超塑性扩散连接和烧结锻造等陶瓷材料的超塑性加工方法，讨论了在陶瓷材料超塑性加工的实际应用中存在的问题，和一些改善陶瓷材料超塑加工性能的方法。     

Superplasticity in ceramics

It is now recognized that superplasticity is a potential deformation process in ceramics. This review summarizes the major characteristics of superplasticity and examines the reports of both transformation and structural superplasticity in ceramic and other non-metallic materials. It is shown that there are both similarities to and differences from metals. Similarities include the variation of strain rate with stress and grain size, but an important difference is the necessity to consider the role of intergranular glassy phases in ceramics. Superplasticity is also important in intermetallic compounds, and in geological materials where there is evidence for superplastic deformation both in laboratory experiments and in natural deformation.     

Improvement of tensile ductility in 3 mol% yttria-stabilized tetragonal zirconia (3Y-TZP) by prestraining

There have been numerous investigations of the effect of material testing variables such as strain rate, temperature and grain size on the elongation to failure of superplastic ceramics. This paper presents information on the effect of rapid prestraining on superplastic ductility in a fine-grained 3 mol% yttria-stabilized tetragonal zirconia (3Y-TZP), using two testing programmes: (i) prestraining up to 130% at a prestrain rate of 1×10-3 s-1 followed by elongation to failure at a test strain rate of 1×10-4 s-1 and (ii) prestraining to 60% at prestrain rates of 1×10-3 s-1 and 2.5×10-4 s-1 followed by elongation to failure at a slower test strain rate of 1×10-4 s-1. The results showed that prestraining at the above conditions considerably improved superplastic ductility as well as reducing the time required to achieve a given elongation. The reason for this ductility enhancement is explained in terms of suppression of grain growth. © 1998 Chapman & Hall     

Ceramics superplasticity

Ceramics superplasticity has been one of the intensive research fields in the last decade. Although most of the reports are still limited to those of zirconia, new developments have been achieved in superplasticity of Si₃N₄ and SiC in recent years. It is clearly demonstrated that the superplasticity is one of the common properties of fine-grained ceramics at elevated temperatures. Superplastic forming and strengthening by superplastic forging are applicable to a wide range of ceramics including oxides, non-oxides, and ceramics with/without intergranular glass phase.     

Superplastic ductility of oxide and nonoxide ceramics

The superplastic ductility of oxide and nonoxide SHS ceramics is considered. It is established that with certain temperature-rate dependences these ceramic materials manifest features typical of superplastic flow. It is shown that the ceramics undergo some specific microstructural changes under strain conditions.Institute of Problems of Metal Superductility, Russian Academy of Sciences, Ufa. Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 65, No. 5, pp. 617–622, November, 1993.     

Ceramics superplasticity: Deformation mechanisms and microstructures

The superplasticity shall be generally achieved by grain refinement of various ceramics (ionic polycrystals and covalent polycrystals). This nature can be utilized for novel deformation processing in ceramic industy, for example, superplastic forming and superplastic forging. The superplasticity is a macroscopic phenomena that is very sensitive to slight difference in atomistic structure, and nature and chemical bonding of grain boundary. The mechanism of superplasticity is grain boundary sliding accommodated by matter transport through grain boundary. The models developed for superplasticity are classified by the structure of grain boundary. The experimental results on superplasticity of Zro₂ and Si₃N₄ were reviewed and compared to the predictions from the theories.     

Some effects of an electric field on the plastic deformation of metals and ceramics

 The external parameters generally considered in the plastic deformation of metals and ceramics are the temperature, pressure or stress and time. Usually neglected are the effects of electric and magnetic fields. However, such fields can often have a significant influence, especially when applied concurrently with the more common parameters. Some examples of the effects of an electric field on the plastic deformation of metals and ceramics found by the author and his coworkers are presented. Included are the following: (a) the influence of electropulsing on the flow stress of metals at 78–300 K, (b) the effect of an external electric field (surface charge) on the superplastic deformation of the 74754 Al alloy, (c) the influence of an electric field on the flow stress and ductility of polycrystalline NaCl at 0.28–0.75 T_M and (d) the effect of an electric field on the superplastic deformation of 3Y-TZP. Mechanisms responsible for the observed effects are considered. Received: 1 January 1998 / Accepted: 1 March 1998     

Seventy-five years of superplasticity: historic developments and new opportunities

On this seventy-fifth anniversary of the first scientific report of true superplastic flow, it is appropriate both to look back and examine the major developments that established the present understanding of superplasticity and to look to the future to the new opportunities that are made possible by new processing techniques, based on the application of severe plastic deformation, that permit the production of fully dense bulk materials with submicrometer or nanometer grain sizes. This review proposes a minor modification to the present definition of superplasticity, it provides an overview of the current understanding of the flow of superplastic metals and ceramics and then it examines, and gives examples of, the new possibilities that are now available for achieving exceptional superplastic behavior.