Print ISSN: 1681-6900

Online ISSN: 2412-0758

Keywords : Corrosion Resistance

Effect of Alloying Elements (Mo and Al) on Biomaterials Ti-Ta Shape Memory Alloys

Fatima J. Al-Hassani; Emad S. Al-Hassani; Sahib M. Al-Saffar

Engineering and Technology Journal, 2014, Volume 32, Issue 4, Pages 932-951

Titanium-Tantalum shape memory materials have widespread potential in biomedical applications In this research the alloy of (Ti-Ta) has been prepared by powder metallurgy technique use fixed percentage of Ta (30 at%), then the alloying elements (Mo and Al) has been added in different compositions (1 at%, 2 at% and 3%) to the master alloy (70% Ti -30% Ta) in order to improve corrosion resistance and mechanical properties . examination were done by using XRD, SEM technique, DSC, Vickers hardness, the porosity percentage and corrosion rate in different solutions (artificial saliva, Ringer solution and blood plasma).The XRD and microstructure results show that all samples with and without additives consist of two phases (β-phase) and (α-phase) at room temperature and the addition of Mo and Al in these percentages does not have effect on present phases. he transformation temperature decreases with the increasing in Mo percentage while this temperature increase with the increasing in Al percentage. The addition of Mo and Al leads to lower the hardness except 3% Mo this sample has highest value than the master sample. The porosity percentage decrease gradually with the increasing in the both Mo and Al percentage due to the better inter diffusion caused by these additives. From the corrosion results in 3% Mo the alloys have less corrosion rate than the master or other percentage (1 at% and 2 at %) In all solutions (artificial saliva, simulated body fluid( Ringer solution) and blood plasma) but the Al has a good corrosion rate in (artificial saliva and blood plasma).

Corrosion Behaviour of Aluminium Alloy 7020-T6 welded Joint in Sea Water at Different Variables

Huda Mohammed Abdulaziz

Engineering and Technology Journal, 2013, Volume 31, Issue 16, Pages 3158-3185

were welded by using inert gas metal arc welding method (MIG)to obtain butt joint
with geometry of single V at 45⁰with two pass.
The joints were tested by X-ray radiography and faulty pieces were excluded.and
the indefectible joints were subjected to stress relief heat treatment including heating
the joint to evaluating temperature 100 C⁰for one hour and air cooling.Optical
microscopy with camera was used to observe the welded joint microstructure.Micro
hardness test were carried out using Vickers instrument to measure the hardness of the
welded joint.
Corrosion behavior of welded jointspecimens in 3.5% NaCl solution at different
media velocity (1, 2, 3) m/min and temperature of (25, 50, 75) ⁰ C for each velocitywas
examined using Tafelpolarization measurements. It is determined byopen circuit
potential (OCP) after that the cell’s current is changed due to the increasing in
potentialby ±100mV to calculate corrosion current then corrosion rate.
The results show that the corrosion rate is increased with increasing solution
temperature. This is because of the prevention of oxygen from dissolving in water,
while the corrosion rate decreases with increasing velocity of sea water since the
movement of the liquid prevents the formation of deposits and ions gathering on
cathode pole where corrosion can easily develop.
when comparing corrosion rate between the welded and unwelded samples, the
welded samples gives more corrosion rate value since the cycle of heating and cooling
that occurs during the welding process affects the microstructure of welds.