Dissertation > Excellent graduate degree dissertation topics show

Investigation on Manufacture of High Temperature Filler Metal and Brazing Technology of TiAl-Based Alloy

Author: WangMing
Tutor: HePeng
School: Harbin Institute of Technology
Course: Materials Processing Engineering
Keywords: TiAl mechanical alloying Ti-Ni filler metal interfacial microstructure shear strength
CLC: TG454
Type: Master's thesis
Year: 2008
Downloads: 101
Quote: 1
Read: Download Dissertation

Abstract


In order to satisfy the requirement of manufacture of aeroengine blades, mechanical alloying was used to produce Ti-Ni filler metal, and then joined TiAl-based alloy. The effects of composition of this alloy on interfacial microstructure and shear strength of the joints were analyzed. Optimal brazing parameters for the alloy were determined.Experimental results show: after mechanical milling, the powder granularity decreases and particle deforms. Grain is refined and lattice distorts. Milled for 480 min, agglomerated particles appear. Atoms diffuse greatly but no new compound was formed.The Ti-50wt.%Ni based alloy milled for 120min can wet TiAl substrate well at the temperature 1140℃, but serious corrosion is observed at fillet. For the joints using Ti-50wt.%Ni based alloy, the interfacial structure of one side is TiAl/Ti3Al+AlNiTi+Ti5Si3/AlNiTi/ incomplete reaction area. AlNiTi layer prevents the atoms from diffusing. The Ti-30wt.%Ni based alloy milled for 120min can also wet TiAl substrate well at the temperature 1100℃, and the serious corrosion isn’t found. The interfacial structure is TiAl/Ti3Al+AlNiTi+ Ti5Si3/TiAl. The heat treatment at 800℃for 20min after bonding has a little influence on the interfacial structure of joints brazed using Ti-Ni alloy.The melting temperature of Ti-50wt.%Ni based alloy decreases with the addition of Al element. However, the quantity of AlNiTi phases increased. And Al element results in the increase of the total melting temperature of Ti-30wt.%Ni based alloy. In one word, the solution of based metal into liquid alloy controls the interface microstructure of joint. Si element can improve the melting and wetting ability of the alloy, and generates Ti5Si3 phase. C element forms TiC, and the effect of TiC phase on dispersion strengthening is better than the one of Ti5Si3 phase, but too much TiC phase results in interfacial defect.For the joints using Ti-50wt.%Ni based alloy, the highest shear strength at room temperature is no more than 200MPa. Fractures propagate between AlNiTi layer and incomplete reaction layer. For the joints using TiH2-30wt.%Ni-0.2wt.%Si alloy brazed at 1100℃for 30min, the shear strength at room temperature and high temperature （800℃） are 230MPa and 185MPa, respectively. And for the joints heat treated at 800℃for 20 min, the shear strength at room temperature is still up to 215MPa. All fracture with Ti-30wt.%Ni based filler metal distributes in the filler metal. For the joints using TiH2-30wt.%Ni-0.1wt.%C alloy brazed at 1140℃for 30 min, the shear strength at room temperature reaches 260MPa.

Related Dissertations

  1. Investigation on Microstructure and Properties of Cadmium-Free Silver-Based Intermediate Temperature Filler Metals,TG425.2
  2. Synthesis of Ag / Al 2 O 3 powder composites research,TB383.3
  3. WCu electrical contact products injection molding process and performance studies,TF124.3
  4. A First-principles Study on the Phase Stability and Elastic Properties of B2-tial Based Alloy,TG146.23
  5. Nb Alloying Effect on the Basic Mechanics Properties of α2, O and β0 Phase in Ti3Al Based Alloy,TG146.23
  6. Study on Preparation of high-performance -doped lanthanum lead zirconate titanate piezoelectric ceramics,TQ174.6
  7. Study on Microstructure Properties and Deformation Behavior at High Temperature of Al-Pb Alloy,TF124.5
  8. TiAl Alloys SPS sintering of Microstructure and High Temperature Oxidation,TF124.5
  9. The Synthesis of B4C Composite and the Research of Its Corrosion Behavior in Sea Water,TG174.3
  10. Structuresand Propertiesand Quality of Tialalloy Billets Directionally Solidified with Cold Crucible,TG111.4
  11. The Study on the Microstucture and the Friction Behavior of 3D-Meshy SiC/20Cr Composite Material,TB332
  12. The Optimal Objective Problem of Stochastic Differential Games,O211.63
  13. The Thermal Stability of a High Nb+Hf Containing TiAl Based Alloy Subjected to a Long-Term Exposure at 700℃ in Air,TG146.23
  14. The Thermal Stability of Refractory-metals Containing γ-TiAl Based Alloys Subjected to a Long-term Exposure 700℃ in Air,TG146.23
  15. Investigation of High Temperature Deformation Behaviors and Microstructure Mechanical Properties of High Nb Containing TiAl Allly with MO,TG132.32
  16. TiB_2, TiAl and TiC nano- powders prepared by mechanical alloying of,TB383.1
  17. Grading milling and vacuum hot pressing sintering high Nb TiAl Alloys,TF124.5
  18. Ti/Al Multilayers Diffusion Bonding γ-TiAl Based Alloy,TG146.23
  19. The Microstructureand Mechanical Properties of Ti-47al-(2,5)Nb Influenced by Y, Gd and Er,TG113
  20. TiAl base alloy rod piece bottom drain vacuum suction casting Process,TG292
  21. Research on the Microstructure and Mechanical Properties of Ti-44Al-6V-3Nb-Y Alloy Pancake and Sheet,TG146.23

CLC: > Industrial Technology > Metallurgy and Metal Craft > Welding, metal cutting and metal bonding > Welding process > Brazing
© 2012 www.DissertationTopic.Net  Mobile