4.1 This guide describes the types of information that are indispensable for uniquely identifying a metal or alloy in a computerized database. The purpose is to facilitate standardized storage and retrieval of the information with a computer, and allow meaningful comparison of data from different sources.
4.2 Many numbering systems for metals and alloys have been developed which are based on their chemical compositions. Separate systems have also evolved to describe the thermomechanical condition of metals and alloys in order to narrow their description. It is the separation into logical data elements from these complex, historically significant, and overlapping systems of identification that is the challenge in the identification of metals and alloys within computerized databases.
4.3 This guide is intended to provide a common starting point for designers and builders of materials property databases. This guide generally identifies the contents of the database in terms of data elements, but does not recommend any particular logical or physical database design. A database builder has considerable flexibility in designing a database schema, and it is intended that this guide support that flexibility.
4.4 It is recognized that material property databases will be designed for different levels of material information and for different purposes. For example, a database developed by an industry trade group might only identify typical properties generally representative of those for a particular metal or alloy, and not actual values measured on a specific sample. On the other hand, a business might desire to manage data on specific lots it procures, or even properties of a specific piece or sample from a lot. Consequently, some of the data elements identified in this guide might not be applicable in every database instance.
4.5 The extent of material identification implemented in a particular database depends on its specific purpose. A single organization may include substantial detail in its database. Less detail may be included in a common database used by several organizations because of commercial and other considerations. Since metals and alloys are diverse and the technologies are always changing, recommendations should not be regarded as exclusive of additional data elements for material identification. The recommended data elements should be expanded if additional detailed information which serves to identify materials is to be recorded.
4.6 A number of data elements are considered essential to any database and need to exist in the database. Data elements are considered essential if they are required for users to have sufficient information to interpret the data and be confident of their ability to compare sets of data for materials from different sources. Failure to complete an essential data element may render the record unusable in a database or in data exchange. Essential refers to the quality or completeness of recorded data, and does not necessarily have direct meaning relative to database structure. In some cases, the identified data element might be accommodated within a particular database without explicitly including a field just for the essential data element. Additionally, a database schema may require additional data fields to be not null to maintain data record integrity or to implement a mandatory d......
他们能否鉴别出一个与生物学信息被编码在DNA碱基对中的方式相同的编码各种化合物属性的“材料基因组”? 如果是这样,Ceder推断,编码肯定存在于构成一种既有材料的原子和电子及其晶体结构中,即它们的空间排列方式。2003年,Ceder和团队首次证实了量子力学计算数据库如何帮助预测一种金属合金最有可能的晶体结构。对于任何从事新材料发明工作的人来说,这都是关键一步。 过去,这些计算冗长且困难。...
除金属识别外,数据库还能够:针对不同条件和温度情况,提供准确、可追踪且可靠的机械、物理等属性数据提供应用指南,其中包括热处理表、可焊性及可加工性数据等,从而避免困难、耗时的无谓人工搜索过程对金属规格进行辨识,找出适合特定应用条件的正确牌号查找外来金属的可替代材料,并对多个可相互替代的同类材料进行并列或交叉比较按照具体化学成分或金属特性在全球查找适合的金属材料指出哪些供应商能够提供所需牌号的材料进行自动更新...
EBSD系统主要由背散射探测器、高灵敏度CCD数字照相机、图像采集卡、计算机分析软件及数据库等组成(图7-2)。探测器用于获取样品中激发出的背散射电子信号;高灵敏度CCD数字照相机获得electron backscat-ter pattern图像后,经过图像采集卡输送到计算机系统。计算机自动对于采集的图像进行识别和标定,同时与标准数据库进行比对,进而获得晶体颗粒的结晶学信息。...
“我们对材料进行量子力学级别的计算,这种计算非常复杂,因此我们可以在实验室中合成一种可能的新材料之前,就用计算机预测出它的属性。”西北大学材料科学家Chris Wolverton说,他主管开放量子材料数据库。其他主要数据库包括材料项目和材料云。数据库还不完整,但数据量一直在增长,并且已经从中找到了令人兴奋的发现。...
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