Source: https://guthlabs.ai/docs/instruments/alloy-density-rule-of-mixtures-calculator/implementation/

instrument implementation / implementation-contract

# Alloy Density Rule-of-Mixtures Calculator implementation

A source-bound implementation contract for Alloy Density Rule-of-Mixtures Calculator; deployment and executable qualification remain separate.

Status: **VERIFIED_CLEAN**Lifecycle: **implementation-contract**

## Binding contract

This record describes what an executable surface must bind and validate. It does not claim that a public calculator, package, or production route is deployed.

**Record owner**: Guth Instruments

**Lifecycle**: verified-clean

**Evidence ID**: t5-036

**Effect**: Computation or source lookup only

## Input and validation requirements

A zero constituent density creates an undefined division in the weight-fraction formula, and ambiguous percentage-versus-unit fraction input can produce a physically nonsensical result if not normalized or rejected.

## Required corrections

No binding erratum is attached to this unique-name record. Implementers must still preserve the declared units, domain, and failure behavior.

## Inspectable interface fixture

The sample below is evidence for interface and validation tests, not a production implementation.

````
{
  "inputs": {
    "mode": "weight_fraction",
    "densities": [
      7.8,
      2.7
    ],
    "density_unit": "g/cm³",
    "fractions": [
      0.7,
      0.3
    ]
  },
  "expected_outputs": {
    "rho_alloy": 4.9787234043,
    "density_unit": "g/cm³"
  },
  "working": "ρ = 1/(0.7/7.8 + 0.3/2.7) = 1/(0.0897435897 + 0.1111111111) = 1/0.2008547008 = 4.9787234043 g/cm³."
}
````

## Other records

[01**Overview**](<https://guthlabs.ai/docs/instruments/alloy-density-rule-of-mixtures-calculator/>)[02**Mechanism**](<https://guthlabs.ai/docs/instruments/alloy-density-rule-of-mixtures-calculator/mechanism/>)[04**Qualification**](<https://guthlabs.ai/docs/instruments/alloy-density-rule-of-mixtures-calculator/qualification/>)

## Sources and evidence

These pointers bind the page to evidence. They do not grant authority or collapse verification into deployment.

- `VERIFIED_LEDGER.json`

- `evidence-tranche5/tranche5-results.json`