Uniaxial loading of different (Ni)TiAl alloy compositions in the <100> direction: A molecular dynamics study

In this study, we analyzed the structure of (Ni)TiAl alloys due to the influence of several variations of alloy compositions during uniaxial loading using molecular dynamics simulation techniques. (Ni)TiAl alloys belong to the family of shape memory alloys and exhibit unique characteristics such as high hardness and rigidity. One of the difficulties in producing such alloys is that liquid titanium is very reactive with oxygen. Therefore, an appropriate material displaying the right properties must be selected to match the usage criteria. To provide a crystal structure in accordance with the wishes or needs of the user, understanding the effects of stress on the crystal structure during tensile testing is crucial. From our simulation results, we found that Ni10%Ti50%Al40% alloy exhibited the highest values of modulus of elasticity, yield stress, and ultimate tensile strength, of 81.21, 6.93, and 9.81 GPa, respectively. The values of these variables decreased with an increase in Ni concentration, meaning that the addition of Ni replacing Al atoms in TiAl alloys decreased the strength but increased the elasticity of the materials. This was verified by the modulus of elasticity values of Ni20%Ti50%Al30% and Ni30%Ti50%Al20% systems, 64.57 and 60.71 GPa, respectively. Massive atomic dislocations upon the system reaching its maximum stress indicated that the system was no longer able to withstand the work done by the surroundings on the system.