First - Principles Study On The Effect Of Alloying Elements On The Mechanical Properties Of AlRu

AlRu alloy has excellent high temperature oxidation resistance and corrosion resistance is the preferred material for military engine components.But AlRu is brittle and difficult to plastic deformation or processing. Therefore, this paper studies the influence of alloying elements on the improvement of AlRu plasticity. According to the calculation results, the selected elements are verified by experiments.In the Al-Ru binary phase diagram,there were Al6Ru、Al13Ru4、Al2Ru、AlRu four intermetallic compounds present at room temperature.This article calculated their shear modulus and bulk modulus based on first-principles density functional theory method and found that four compounds belonging brittle material. since G/B values were more than 0.5. but AlRu intermetallic compound was the best plastic material of the four compounds. Analysis of the AlRu state density showed that the 3P orbitals of Al atom、3P orbitals of Ru atom and 4d orbitals of Ru atom appeared hybridization.The probability that electrons participate in the bonding was increased, the system becamed more stable.Further calculation on population found the Al-Ru bond was positive.It may lead to the formation of more covalent bonds, reducing the AlRu of the plastic.To observe the electron cloud of Ru atoms, found it was a typical petal and outer electron distribution presented anisotropy,which also lead to the decrease of AlRu plasticity.In order to improve the plasticity of AlRu,we selected doping Cr、Mn、Co、Mo、 V、Ti、Ta、Ni、W、Re ten kinds of replacement type atom and interstitial atom B as an alloying element and studied their effects on AlRu plastic properties. substitutional atoms Cr, Mn, Co, Mo, V, Ti, Ta, Ni, W, Re, established atomic percent content 1.56at%,3.125at% 6.25at% three models.The results showed that G/B value was the lowest,when the element content was 6.25at%,but only Re, Ti, W, Co, Mo five elements can improve its plasticity, especially the effect of Co, Mo elements was the best.This paper established a mass content 0.178wt%,0.238wt%,0.475wt% and 0.711wt% four octahedral models for gap atom B.It was found G/B value with the increase of the B element content change increased at first and decreased subsequently.the minimum value (0.467) appeared in the B content of 0.475wt%.This was lower than 6.25at%Co element (0.473)which was the best effect in doped replacement type alloy atoms.By means of the analysis of the density of states to those in favor of toughness element, it was shown that the electron hybridization between p and d orbitals was decreased and the system stability was also decreased.The Al-Ru bond energy was reduced, and generated Ru-Ru antibonding bond is formed,through analysis of population and difference charge density. Moreover,the outer electron distribution anisotropy of Ru atom was weakened.These variations were conducive to enhancement of AlRu plastic.B element which was the best effect of improving the AlRu plasticity was selected to verify in the experimental section.This article prepared five samples by spark plasma sintering, which B content was respectively 0wt%,0.2wt%,0.5wt%, 0.7wt% and 3wt%.the sample morphology was observed with SEM and Young’s modulus and shear modulus were measured by nano indentation tester and universal testing machine,Then calculated G/B value.The results showed that the sample tissue distribution was uniform,but there were some gaps.Although the shear modulus and bulk modulus are lower than the calculated values, the change trend of G/B value with the increase of B element content is basically consistent with the calculation results.