Preface

Chapter 8 **Control the Metal Grain Boundary Recrystallization Evolution**

**Cyclic Thermal Loading 161** Makin Vladimir Sergeevich

**VI** Contents

**by the Laser Radiation Electric Field Strength Direction Under**

The grain boundary in a solid material is an interface between two crystals (grains) of the same phase. The mechanical strength and physical properties of industrial materials not on‐ ly depend on the properties of their components but also are driven by the transition region between two adjacent crystals (boundaries), in particular the chemical constitution and structure of the boundaries. The majority of conventionally used materials are generally pol‐ ycrystalline; thus, their properties are related not only with the size of grains but also with the grain boundaries. Moreover, modern technological requirements for materials that are "free from defects" and those with high structure defect density make it essential to thor‐ oughly understand the nature of grain boundaries and their influences on the physical and mechanical properties.

#### **Tomasz Tański and Wojciech Borek**

Institute of Engineering Materials and Biomaterials Silesian University of Technology Gliwice, Poland

#### **The Effect of Impurities in Nickel Grain Boundary: Density Functional Theory Study The Effect of Impurities in Nickel Grain Boundary: Density Functional Theory Study**

Iben Khaldoun Lefkaier and El Tayeb Bentria Iben Khaldoun Lefkaier and El Tayeb Bentria

Additional information is available at the end of the chapter Additional information is available at the end of the chapter

http://dx.doi.org/10.5772/66427

#### **Abstract**

By means of density functional theory, we investigate the effect of impurities on structural, electronic and mechanical properties on Nickel Σ5 grain boundary (GB) and its free surface, by studying the effect of 11 transition metal impurities and 8 light elements. The calculation of segregation energy, cohesive energy, formation energy, GB embrittling potency and theoretical tensile strength combined helps us to give accurate conclusions about the effect of these impurities and to compare them with the available experimental and theoretical results. We used the obtained results that are on "equal footing" to establish some correlations and trends. We also confirmed that sulfur and oxygen are the most embrittling elements in Nickel GB in accordance with established literature results and that transition metal elements have a general tendency to segregate to the grain boundaries in a moderate way. Unlike the studied light elements, these elements tend to strengthen the Ni grain boundaries, especially W and Te.

**Keywords:** nickel grain boundaries, DFT, tensile strength, impurities segregation
