Welcome to week 2! In lesson three we will discover how dislocations at the atomic-level structure of materials explain plastic (permanent) deformation. You will learn to define a linear defect and see how materials deform through dislocation motion. Lesson four compares stress versus strain, and introduces the “Big Four” mechanical properties of elasticity, yield strength, tensile strength, and ductility. You’ll assess what happens beyond the tensile strength of an object. And you’ll learn about a fifth important property – toughness.

Welcome to week 3! In lesson five we’ll explore creep deformation and learn to analyze a creep curve. We’ll apply the Arrhenius Relationship to creep deformation and identify the mechanisms of creep deformation. In lesson six we find that the phenomenon of ductile-to-brittle transition is related to a particular crystal structure (the body-centered cubic). We’ll also learn to plot the ductile-to-brittle transition for further analysis.

Welcome to week 4! In lesson seven we will examine the concept of critical flaws. We’ll define fracture toughness and critical flaw size with the design plot. We’ll also distinguish how we break things in good and bad ways. Lesson eight explores the concept of fatigue in engineering materials. We’ll define fatigue and examine the fatigue curve and fatigue strength. We’ll also identify mechanisms of fatigue.

Welcome to week 5! In lesson nine we’ll deal with how to make things fast and slow. We’ll examine the lead-tin phase diagram and look at its practical applications as an example of making something slowly. Then we’ll evaluate the TTT diagram for eutectoid steel, and compare diffusional to diffusionless transformations with the TTT diagram, monitoring how we make things rapidly. Lesson ten is a brief history of semiconductors. Here, we discuss the role of semiconductor materials in the modern electronics industry. Our friend Arrhenius is back again, and this time we’re applying the Arrhenius Relationship to both intrinsic and extrinsic semiconductors. We’ll also look at combined intrinsic and extrinsic behavior.