1.1 本规程涵盖了与测定主要均匀各向同性固体材料的热扩散率相关的实用细节。热扩散率值范围为10 –7 至10 -3 m 2. /从大约75 K至2800 K 1.2 本规程是对试验方法的补充 E1461 . 1.3 本规程适用于在能量脉冲频谱不透明的材料上进行的测量，但在采取特殊预防措施后，可在完全或部分透明的材料上使用。 1.4 本规程旨在允许多种设备设计。在此类文件中，建立施工细节和程序以涵盖可能给缺乏相关技术知识的人带来困难的所有意外事件，或停止或限制用于改进基本技术的研究和开发，是不现实的。 本规程为此类仪器的构造原理、优选实施例和操作参数提供了指南。 1.5 本规程适用于在基本完全密实的材料上进行的测量；然而，在某些情况下，当与多孔试样一起使用时，它可以产生可接受的结果。由于孔隙度的大小、孔隙形状和孔隙分布参数会影响热扩散率的行为，因此在分析数据时必须格外小心。当其他特性（如导热系数）由该方法获得的热扩散率得出时，建议特别小心。 1.6 由于不需要参考材料，闪光灯可被视为绝对（或主要）测量方法。 建议仅使用参考材料来验证所用仪器的性能。 1.7 严格来说，该方法仅适用于均质固体材料；然而，在某些情况下，它可以产生在某些应用中有用的数据: 1.7.1 复合材料试验- 当材料中存在实质性的不均匀性和各向异性时，使用该方法获得的热扩散率数据可能存在实质性误差。然而，这些数据虽然通常缺乏绝对准确性，但在比较类似结构的材料时可能有用。当导出相关属性（例如导热性）时，必须格外小心，因为复合材料的热流模式可能与单轴材料有很大不同。 如果与试样厚度相比，复合相的粒径较小（约为厚度的1%至25%），并且与模型相比，试样的瞬态热响应似乎均匀，则该方法可以产生复合材料的准确结果。各向异性材料可以通过各种技术进行测量，只要定向热扩散系数（二维或三维）相互正交，并且测量和试样制备仅沿一个主方向产生热流。此外，可以使用2D和3D模型以及一个或两个方向上的独立测量，或同时测量试样表面不同位置的温度响应。 1.7.2 测试液体- 该方法在测定熔融材料的热扩散率方面有着特别有用的应用。对于这种技术，必须使用特殊构造的样本外壳。 1.7.3 测试分层材料- 该方法还被扩展到测试由不同材料制成的某些层状结构，其中一层的热特性被视为未知。在某些情况下，还可以确定界面的接触电导。 1.8 以国际单位制表示的数值应视为标准值。本标准不包括其他计量单位。 1.9 本标准并非旨在解决与其使用相关的所有安全问题（如有）。本标准的用户有责任在使用前制定适当的安全、健康和环境实践，并确定监管限制的适用性。 1.10 本国际标准是根据世界贸易组织技术性贸易壁垒（TBT）委员会发布的《关于制定国际标准、指南和建议的原则的决定》中确立的国际公认标准化原则制定的。 ====意义和用途====== 5.1 热扩散率是一个重要的特性，在瞬态热流条件下，如设计应用、安全工作温度的确定、过程控制和质量保证等，需要用于此类目的。 5.2 闪光法用于测量各种固体材料的热扩散系数α值。由于试样几何形状简单、试样尺寸要求小、测量速度快且易于处理，因此它特别具有优势。 5.3 在某些严格条件下，当以定量方式使用该方法时，可以确定均质各向同性不透明固体样品的比热容（见试验方法 E1461 ，附录1）。 5.4 热扩散率结果以及比热容的相关值( C p )和密度（ρ）值，在许多情况下可以根据以下关系得出热导率（λ）:

1.1 This practice covers practical details associated with the determination of the thermal diffusivity of primarily homogeneous isotropic solid materials. Thermal diffusivity values ranging from 10 –7 to 10 -3 m 2 /s are readily measurable by this from about 75 K to 2800 K. 1.2 This practice is adjunct to Test Method E1461 . 1.3 This practice is applicable to the measurements performed on materials opaque to the spectrum of the energy pulse, but with special precautions can be used on fully or partially transparent materials. 1.4 This practice is intended to allow a wide variety of apparatus designs. It is not practical in a document of this type to establish details of construction and procedures to cover all contingencies that might offer difficulties to a person without pertinent technical knowledge, or to stop or restrict research and development for improvements in the basic technique. This practice provides guidelines for the construction principles, preferred embodiments and operating parameters for this type of instruments. 1.5 This practice is applicable to the measurements performed on essentially fully dense materials; however, in some cases it has shown to produce acceptable results when used with porous specimens. Since the magnitude of porosity, pore shapes, and parameters of pore distribution influence the behavior of the thermal diffusivity, extreme caution must be exercised when analyzing data. Special caution is advised when other properties, such as thermal conductivity, are derived from thermal diffusivity obtained by this method. 1.6 The flash can be considered an absolute (or primary) method of measurement, since no reference materials are required. It is advisable to use only reference materials to verify the performance of the instrument used. 1.7 This method is applicable only for homogeneous solid materials, in the strictest sense; however, in some cases it has been shown to produce data found to be useful in certain applications: 1.7.1 Testing of Composite Materials— When substantial non-homogeneity and anisotropy is present in a material, the thermal diffusivity data obtained with this method may be substantially in error. Nevertheless, such data, while usually lacking absolute accuracy, may be useful in comparing materials of similar structure. Extreme caution must be exercised when related properties, such as thermal conductivity, are derived, as composite materials, for example, may have heat flow patterns substantially different than uniaxial. In cases where the particle size of the composite phases is small compared to the specimen thickness (on the order of 1 to 25 % of thickness) and where the transient thermal response of the specimen appears homogenous when compared to the model, this method can produce accurate results for composite materials. Anisotropic materials can be measured by various techniques, as long as the directional thermal diffusivities (two dimensional or three dimensional) are mutually orthogonal and the measurement and specimen preparation produce heat flow only along one principle direction. Also, 2D and 3D models and either independent measurements in one or two directions, or simultaneous measurements of temperature response at different locations on the surface of the specimen, can be utilized. 1.7.2 Testing Liquids— This method has found an especially useful application in determining thermal diffusivity of molten materials. For this technique, specially constructed specimen enclosures must be used. 1.7.3 Testing Layered Materials— This method has also been extended to test certain layered structures made of dissimilar materials, where the thermal properties of one of the layers are considered unknown. In some cases, contact conductance of the interface may also be determined. 1.8 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard. 1.9 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use. 1.10 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee. ====== Significance And Use ====== 5.1 Thermal diffusivity is an important property, required for such purposes under transient heat flow conditions, such as design applications, determination of safe operating temperature, process control, and quality assurance. 5.2 The flash method is used to measure values of thermal diffusivity, α, of a wide range of solid materials. It is particularly advantageous because of simple specimen geometry, small specimen size requirements, rapidity of measurement and ease of handling. 5.3 Under certain strict conditions, specific heat capacity of a homogeneous isotropic opaque solid sample can be determined when the method is used in a quantitative fashion (see Test Method E1461 , Appendix 1). 5.4 Thermal diffusivity results, together with related values of specific heat capacity ( C p ) and density (ρ) values, can be used in many cases to derive thermal conductivity (λ), according to the relationship: