943 resultados para Pure
Resumo:
Long-length ultrafine-grained (UFG) Ti rods are produced by equal-channel angular pressing via the conform scheme (ECAP-C) at 200 °C, which is followed by drawing at 200 °C. The evolution of microstructure, macrotexture, and mechanical properties (yield strength, ultimate tensile strength, failure stress, uniform elongation, elongation to failure) of pure Ti during this thermo-mechanical processing is studied. Special attention is also paid to the effect of microstructure on the mechanical behavior of the material after macrolocalization of plastic flow. The number of ECAP-C passes varies in the range of 1–10. The microstructure is more refined with increasing number of ECAP-C passes. Formation of homogeneous microstructure with a grain/subgrain size of 200 nm and its saturation after 6 ECAP-C passes are observed. Strength properties increase with increasing number of ECAP passes and saturate after 6 ECAP-C passes to a yield strength of 973 MPa, an ultimate tensile strength of 1035 MPa, and a true failure stress of 1400 MPa (from 625, 750, and 1150 MPa in the as-received condition). The true strain at failure failure decreases after ECAP-C processing. The reduction of area and true strain to failure values do not decrease after ECAP-C processing. The sample after 6 ECAP-C passes is subjected to drawing at 200¯C resulting in reduction of a grain/subgrain size to 150 nm, formation of (10 
1¯0) fiber texture with respect to the rod axis, and further increase of the yield strength up to 1190 MPa, the ultimate tensile strength up to 1230 MPa and the true failure stress up to 1600 MPa. It is demonstrated that UFG CP Ti has low resistance to macrolocalization of plastic deformation and high resistance to crack formation after necking.
Resumo:
This paper examines the roots and properties of Herbert Bayer’s chromatic paintings completed between 1966 and 1976. This series of paintings is grounded in advanced theories of color and geometry, first introduced to Bayer as a young architecture apprentice and later developed at the Bauhaus. An investigation of Bayer’s mature reassessment of those early Bauhaus teachings in color theory and the development of his own color system is the underlying focus of this paper. The purpose of this study is to shed light on the significance of the chromatics that have received little attention to date.
Resumo:
In light of the growing international competition among states and globally operating companies for limited natural resources, export restrictions on raw materials have become a popular means for governments to strive for various goals, including industrial development, natural resource conservation and environmental protection. For instance, China as a major supplier of many raw materials has been using its powerful position to both economic and political ends. The European Union (EU), alongside economic heavyweights such as the US, Japan and Mexico, launched two high-profile cases against such export restrictions by China at the WTO in 2009 and 2012. Against this background, this paper analyses the EU’s motivations in the initiation of trade disputes on export restrictions at WTO, particularly focusing on the two cases with China. It argues that the EU's WTO complaints against export restrictions on raw materials are to a large extent motivated by its economic and systemic interests rather than political interests. The EU is more likely to launch a WTO complaint, the stronger the potential and actual impact on its economy, the more ambiguous the WTO rules and the stronger the internal or external lobbying by member states or companies. This argumentation is based on the analysis of pertinent factors such as the economic impact, the ambiguity of WTO law on export restrictions and the pressure by individual member states on the EU as well as the role of joint complaints at the WTO and political considerations influencing the EU’s decision-making process.
