NPTEL Course: Defects in Crystalline Solids Part-II by IIT Kanpur | Dislocations

Course Details

Master the Mechanics of Materials: Defects in Crystalline Solids (Part-II)

Welcome to the second part of the comprehensive journey into the world of crystalline imperfections. Building upon the foundational concepts introduced in Part-I, this advanced course, Defects in Crystalline Solids (Part-II), delves deep into the core of material behavior: dislocations and their profound impact on mechanical properties. Offered by NPTEL and instructed by Prof. Shashank Shekhar from IIT Kanpur, this 4-week program is designed to transform your understanding of why materials deform, strengthen, and fail.

Course Overview & Instructor Profile

This course is a critical continuation for students and professionals aiming to grasp the micro-mechanisms governing material strength and plasticity. Over four intensive weeks, you will move from basic dislocation theory to advanced concepts linking defects to real-world material performance.

Your guide for this exploration is Prof. Shashank Shekhar, an Associate Professor at IIT Kanpur with over a decade of teaching experience in manufacturing and materials courses. His research expertise in thermomechanical processing and severe plastic deformation techniques like machining brings a practical, application-oriented perspective to the theoretical concepts, ensuring you learn not just the 'what' but the 'why' and 'how' of material defects.

Who Should Enroll?

This course is perfectly tailored for:

• Undergraduate and first-year graduate students in Materials Engineering, Metallurgical Engineering, and Mechanical Engineering.
• Students from related disciplines like Industrial Engineering and Electrical Engineering seeking a solid foundation in materials science.
• Early-career engineers and researchers in industries where material selection, failure analysis, and process optimization are crucial.

Prerequisites & Industry Relevance

To succeed, you should have a background in undergraduate-level mathematics and thermodynamics. Recommended NPTEL courses for preparation include Engineering Mathematics I & II and Thermodynamics.

The knowledge gained has direct industry applications in:

• Manufacturing & Automobile Companies: For designing stronger, lighter components.
• Iron, Steel, & Alloy Producers: For developing advanced high-strength materials.
• Equipment Manufacturers: For predicting fatigue life and improving durability.

Detailed Course Curriculum: A Week-by-Week Breakdown

Week 1: Dislocations in Face-Centered Cubic (FCC) Systems

Dive into the specifics of dislocation behavior in common FCC metals like aluminum and copper. Key topics include:

• Partial Dislocations and Stacking Faults
• Thompson’s Tetrahedron as a visualization tool
• Formation of barriers like the Cottrell Lock and Lomer-Cottrell Lock
• Complex interactions through the intersection of extended dislocations

Week 2: Dislocations in BCC, HCP, and Complex Structures

Expand your knowledge to other critical crystal systems:

• Unique characteristics of dislocations in Body-Centered Cubic (BCC) metals (e.g., iron) and Hexagonal Close-Packed (HCP) metals (e.g., magnesium, titanium).
• Challenges of dislocations in Superlattices (ordered intermetallics).
• The concept of Kear-Wilsdorf Locks in strengthening high-temperature alloys.

Week 3: Dislocation Interactions and Strengthening Mechanisms

This week connects microscopic defects to macroscopic strength. Learn how obstacles at the atomic scale make materials tougher:

• Interaction of dislocations with point defects (vacancies).
• Core strengthening mechanisms:
  • Strengthening by interfaces (grain boundaries).
  • Strengthening by precipitates and inclusions (precipitation hardening).
• Fundamental mechanisms of dislocation generation and multiplication.

Week 4: Dislocations, Grain Boundaries, and Advanced Models

Conclude with the critical role of interfaces and advanced dislocation concepts:

• Structure of Grain Boundaries and their energy.
• The Read-Shockley model for Low-Angle Grain Boundaries (LAGBs).
• Coincident Site Lattice (CSL) boundaries and secondary dislocations.
• Distinguishing between Geometrically Necessary Dislocations (GNDs) and Statistically Stored Dislocations (SSDs) – key for understanding strain gradients and plasticity at small scales.

Learning Outcomes

Upon successful completion of this course, you will be able to:

• Analyze and predict dislocation behavior in specific crystal systems (FCC, BCC, HCP).
• Explain the fundamental mechanisms behind major material strengthening techniques.
• Model the energy and structure of grain boundaries based on dislocation theory.
• Apply these concepts to understand material selection, processing effects, and mechanical performance in engineering applications.

Enroll in Defects in Crystalline Solids (Part-II) today and take a significant step towards mastering the hidden architecture that defines the strength and durability of every engineered material around you. Bridge the gap between atomic-scale defects and world-class engineering solutions.

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