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Containing Nb, RE and Si, TiAl alloy ingots cold crucible side directional solidification

Author: YanYunCheng
Tutor: DingHongSheng
School: Harbin Institute of Technology
Course: Materials Processing Engineering
Keywords: Strong plastic values Directional solidification Solid-liquid interface Active temperature gradient Passive temperature gradient Lamellar structure Precipitates Cleavage Wear layer fracture
CLC: TF807
Type: Master's thesis
Year: 2009
Downloads: 57
Quote: 0
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Abstract


This article TiAl alloy buttons furnace experiments done by compression experiments to determine the different components of the strength and plasticity button ingots , which were calculated for each button ingots strong plastic value, according to the value of a strong plastic components to make sure the size of directional solidification experiments . In this paper, the distribution of the six categories of 18 kinds of chemical constituents elected Ti47Al5Nb0.3Y0.5Si do directional solidification experiments on directional solidification of the alloy forming process macro , microstructure and mechanical properties . 26 × 26mm square water-cooled copper crucible directional solidification experiments take six kinds forming process were prepared six ingot . Macrostructure ingot can be divided into three regions: the primary area, growing area and the final solidification zone . Found through experiments macroscopic solid-liquid interface morphology on the growth direction of the columnar grains have a direct impact, and the macroscopic solid-liquid interface shape forming process can be controlled . The essence of solid-liquid interface is an active temperature gradient and temperature gradient two conflicting passive configuration, active temperature gradient is an electromagnetic induction heating temperature gradient , the temperature gradient is passively cooled copper crucible cooling temperature gradient and the cooling liquid gallium indium alloy temperature gradient . Active temperature gradient exists presupposes the existence of a passive temperature gradient . A longitudinal section through a scanning electron photomicrograph and discovery : Alloy the α2, γ two phase composition, and γ -phase lamellar structure has three ( and , respectively, the growth direction of the columnar crystal was 0 °, 45 °, and 90 °), this shows that the occurrence of two solid phase transformation ; film thickness for γ found to improve both the power and the pulling speed can refine the lamellae . This shows not only to control the solid-liquid interface morphology also possible refinement layers , because columnar grain growth direction , the direction and the lamellar lamellar thickness on the mechanical properties of alloys have a significant impact . The study found that for precipitates , process for Y and Si precipitates distribution and composition is almost no effect , while the Y and Si precipitates can refine the grain . At room temperature and high temperature of 850 ℃ tensile tests showed P = 45kW, V = 1.2mm/min optimum mechanical properties , and mechanical properties of high-temperature experiment is better than room temperature mechanical properties of the experimental mechanism for further study. Experimental study found that the fracture mode fracture scanning mainly cleavage fracture and wear layers .

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CLC: > Industrial Technology > Metallurgical Industry > Nonferrous metal smelting > General issues > Ingot
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