Mechanical deformation, titanium

Alloys are solid metallic mixtures designed to meet specific needs (see Section 5.15). For example, the frames of racing bicycles can be made of a steel that contains manganese, molybdenum, and carbon to give them the stiffness needed to resist mechanical shock. Titanium frames are used, but not the pure metal. Titanium metal stretches easily, so much so that it becomes deformed under stress. However, when alloyed with metals such as tin and aluminum, titanium maintains its flexibility but keeps its shape. 

R-phase, which serves as an intermediate phase to facilitate the transformation between martensite and austenite. Formation of the R-phase is reported to arise from the presence of dislocations and precipitates [11]. A substantial dislocation density is expected in the vwought nickel-titanium endodontic instruments and orthodontic wires, which are subjected to extensive mechanical deformation during manufacturing processes [12], Microstructural precipitates are a consequence of the inevitable deviation of the nickel-titanium alloy composition from the equi-atomic NiTi composition [13,14],... 

Cryogenic milling is a top-down approach to prepare nanoscale titanium of 100-300 nm size. Several mechanical deformations of large grains into nltra fine powder and degassing lead to nanopowder with improved characteristics. 

H Kurishita, K Nakajima, H Yoshinaga. The high temperature deformation mechanism in titanium carbide single crystals. Mater Sci Eng 54 177, 1982. 

The evaluation and demonstration of this weldi ng technique was accomplished in three phases evaluation and optimization of ten major expl welding variables (plate material, plate thickness, explosive quantity standoff, plate surface, plate deformation, mechanical shock, metal grain orientation, weld length, and expl residual), the development of four welu joints, and an a fplicationai analysis which included photomicrographs, pressure integrity tests, vacuum effects, and fabrication of some potentially useful structures in aluminum and titanium... 

Polybutylene therephthalate (PBT) has been used as a blend component to provide chemical resistance in various systems, but the most interesting one results from a combination with polycarbonate and, eventually, an Impact modifier of the coreshell type. Polyester blends containing polycarbonate exhibit ester interchange chemical reactions, which add to the complexity of property control of these materials. DEVAUX and co-workers (14) have examined the transesterification reaction catalysed by residual catalysts in PBT which can lead to the formation of block and random copolymers. They have shown that allyl or aryl phosphites inactivate the residual titanium catalyst and minimise the transesterification reaction. HOBBS et al. (15) reported a way of controlling miscibility behaviour, morphology and deformation mechanisms, in order to obtain blends compati-bilisation and excellent mechanical properties. 

Key words Titanium discontinuous composites, microstructure, mechanical properties, plastic deformation. 

The titanium-based composites with discontinuous reinforcement are attractive materials for a wide range of applications because of their high specific strength and stiffness and good fracture-related properties. Mechanical behavior of these materials depends strongly on both composition and microstructure of matrix and type, size and volume fraction of reinforcing phase. Hot plastic deformation is a powerful tool enhancing mechanical properties of titanium alloys. 

The stated considerations are correct for titanium. In titanium alloys evolution of lamellar microstructure (typical for titanium alloys) takes place due to development of globularization [8], The process develops by means of substructure formation in the lamellas of phases, division of lamellas and transformation of lamellas parts into globular particles. Keep the process its main features in the case of SMC structure formation There are no such investigations in the scientific literature. The relative simplicity of the method and its commercial application bring up a question to investigate the features of microstructure evolution and mechanical behavior of titanium and its alloys during successive deformation/rotation of samples as well as scale up process capability for production of SMC structure in large-scale billets and sheets. 

Table lc.l5 Influence of a cold deformation on the mechanical properties of P-titanium alloys (Ref. 5)... 

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