What Is the Avrami Isothermal Phase Transformation Kinetics Calculator?
The Avrami equation describes how a new thermodynamic phase nucleates and spreads through a parent phase over time at constant temperature.
It accounts for "phantom" volume overlap as growing crystal grains impinge against each other.
How Does the Avrami Isothermal Phase Transformation Kinetics Calculator Work?
Computes transformed fraction X(t) between 0% and 100%.
Determines the half-life time t0.5 where exactly 50% of the volume is transformed.
Evaluates the instantaneous reaction rate dX/dt.
Avrami Isothermal Phase Transformation Kinetics Calculator Formula & Variables
The core mathematical equation utilized by this calculator is expressed as:
JMAK statistical nucleation and growth phase transformation model with geometric impingement correction.
How to Use the Avrami Isothermal Phase Transformation Kinetics Calculator
- Enter elapsed holding time in minutes.
- Provide Avrami rate constant k and Avrami growth exponent n.
Step-by-Step Example Calculation
Isothermal Austenite-to-Bainite Transformation
Input Values:
Understanding Your Result
Transformed percentage indicates volume fraction of the new microstructural constituent.
Sigmoidal transformation displays an initial incubation lag, rapid mid-stage growth, and slow late-stage completion.
Factors That Affect the Result
- Holding temperature: Under-cooling drives nucleation rate while diffusion controls growth velocity (producing C-shaped TTT curves).
- Avrami exponent n: n=3 implies 3D diffusion-controlled growth; n=4 implies interface-controlled growth with continuous nucleation.
When Should You Use This Calculator?
- Constructing Time-Temperature-Transformation (TTT) diagrams for heat treatment of steels and alloys.
- Polymer crystallization kinetics and glass-ceramic processing.
Assumptions & Limitations
- Assumes strictly isothermal conditions without thermal gradients.
- Assumes spatially random nucleation sites.
Frequently Asked Questions
Calculation Accuracy & Reference Note
Standard kinetic formulation across materials science and metallurgical engineering.