Effect of nanostructure TiO2 addition and heat treatment on the Structural and mechanical Properties of Al- 4wt. % Ag Alloy.

Abstract

The present work mainly covers studying the essence of adding TiO2 nanoparticles on the structural and mechanical properties of Al- 4 wt.% Ag alloy. Three topics are discussed:

1) Studying the effect of TiO2 nanoparticles addition on structural characteristics of Al- 4 wt.% Ag alloy.

2) Studying the effect of strain rate ε• and testing temperatures T on the stress-strain characteristics of Al- 4 wt.% Ag alloy and Al- 4 wt.% Ag-0.1wt.% TiO2 alloy wire samples.

3) Studying creep characteristics of the two alloys. The experimental results were investigated under different levels of stress and temperature.

In the first topic, Studying the structure evolutions of both Al- 4 wt.% Ag alloy and Al- 4 wt.% Ag-0.1wt.% TiO2 alloy were discussed (XRD). The results showed that the values of the lattice parameter ao reached maximum value at the deformation peak (maximum lattice strain). The addition of 0.1wt.% nano-sized TiO2 particles to Al-4wt.% Ag alloy cause the disappearance hard phases of AlAg3 and Ag2Al (hcp) (inter-metallic compounds) as shown in X-ray diffraction patterns and appear AlTi phase (tetragonal)which is less hardening than the hcp phase..

In the second topic, stress-strain tests for Al- 4 wt.% Ag and Al- 4 wt.% Ag-0.1wt.% TiO2 alloys were performed under the effect of different strain rates ε• ranged from 3 x 10-4 to 9x 10-4 s-1 at different testing temperatures T in the range of 603 to 663 K. The results showed that increasing strain rates and decreasing the testing temperatures resulted in increasing the hardening parameters ultimate tensile stress UTS, yield stress y , fracture stress f , time of fracture tf and work hardening coefficient χ and decreasing the softening parameters strain fracture εf and dislocation slip distance L. Also the existence of the nano-sized TiO2 particles resulted in decreasing the hardening parameters ultimate tensile stress UTS, yield stress y , fracture stress f , time of fracture tf and work hardening coefficient χ and increasing the softening parameters strain fracture εf and dislocation slip distance L.