Theoretical Study Of The Bulk Modulus For Fe And Al Metals With The MAEAM Model

The elastic properties of materials play an essential role in the aspect of engineering design and application,scientific research et al.Also,it is the primary foundation for the evaluation and the preference of metal materials and the processing technical option of materials.For the development of society and the national defense,such as modern aviation and space industry,radio industry, precise instrument and precision meter industry,there are great higher demands for the elastic properties of the metals materials.That is to say,the elastic modulus of the metals materials must be higher and invariable.Therefore,we much try our best to improve the properties of the metal materials continuously,to explore the new metal materials and the new alloys materials,and to develop the metals and the alloy composite materials with the properties of ultra-high strength and malleability,high corrosion resistant,superheat resisting and high modulus.The Modified Analytical Embedded Atom(MAEAM)Model and the anharmonic effect are used to study the bulk modulus of FCC Al metal and BCC Fe metal.In the paper,the following results are obtained:1.The bulk modulus calculated by the MAEAM model for BCC Fe metal and FCC Al metal at zero temperature is in good agreement with the experiment data available.It indicates that the MAEAM model can be applied to investigate the bulk modulus for BCC Fe metal and FCC Al metal. 2.Considering the anharmonic effect,applying the MAEAM model and the anharmonic theory,the variation of the bulk modulus with temperature can be described successfully.That is,the bulk modulus for BCC Fe metal can be described by a quadratic function of temperature B[T]= 1.732-1.871×10^-4T + 7.333×10^-11T², And the bulk modulus for FCC Al metal can be described by a quadratic function of temperature B[T]=0.802 - 1.236×10^-4T + 3.275×10^-11T².The result demonstrates the feasibility of the present method.3.The MAEAM model and the anhannonic theory are used to study the bulk modulus and we find that the bulk modulus increases with the pressure for Fe metal.The relationship can be described by a quadratic function of pressure B = 1.732×10¹¹+ 7/9 P+ 7.927×10¹¹ln(P×5.773×10^-12+ 1),and the result is in good agreement with the data available.When the pressure is less than 4×10¹¹pa,pressure have nothing to do with the harmonic coefficient and the second anharmonic coefficient. The B-P curve is flat within the pressure less than 10¹¹Pa,That is to say,with the increase of the pressure,the bulk modulus grow slowly.And there will be a great steep B-P curve when the pressure is greater than 10¹²Pa.The bulk modulus increases greatly with the increases of the pressure.These can be explained with the interatomic interaction:when the pressure is small,there is great interatomic distance,and the attractive force is relatively bigger.With the increase of pressure, the interatomic distance decreased,and the repulsive force is predominate gradually;with the continually increasing of pressure,the repulsive force increased greatly,it's becoming very difficult to compress,and the bulk modulus is therefore reinforced greatly.The result demonstrates the influence of the pressure on the bulk modulus for Fe metal.