Encyclopedia Materials Materials Shape Memory Alloy From Jcost

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Materials Shape Memory Alloy From Jcost

A shape memory alloy snaps back to its original shape when heated, and a framework called Recognition Science offers a formula for the temperature gap behind that snap.

Shape memory alloys and the cost threshold

A shape memory alloy (SMA) is a metal that can be bent out of shape at a low temperature and then return to its original shape when heated. The classic example is nitinol, a nickel-titanium alloy. The effect happens because the material changes internal crystal structure: at low temperature it is in a martensitic phase, soft and easily deformed, and when heated past a transformation temperature it reverts to a stronger austenitic phase. The transformation does not occur at a single temperature; it shows hysteresis, meaning the forward and reverse transformations happen at different temperatures. For nitinol, the measured width of this hysteresis gap is typically 20 to 40 degrees Celsius.

Recognition Science is a framework that starts from the idea that reality keeps a ledger, a discrete record of recognition events, and that the cost of recognition is forced by a small set of conditions. From those conditions the framework proves a unique cost function, J(x) = (x + 1/x)/2 - 1. The framework's library, a machine-checked collection of formal theorems, contains a module that applies this cost function to shape memory alloys. The module defines a domain cost, the cost associated with a mismatch between two quantities m and e, as J(m/e).

In the module, the two quantities are meant to be the martensitic transformation temperature T_ms and the hysteresis width ΔT. The framework's research note records the intended relation: ΔT = J(φ) × T_ms ≈ 0.118 × 200°C ≈ 24°C. The number 0.118 comes from evaluating the cost function at the golden ratio φ, and 200°C is a typical transformation temperature for nitinol. The result, about 24°C, falls inside the measured 20 to 40°C range for nitinol hysteresis. This is an empirical check, not a theorem.

What the module actually proves is more modest and fully general. It proves three facts about the cost function for any positive inputs: the cost is zero when m equals e, the cost is never negative, and the threshold value φ - 3/2 is positive. The module defines a certificate structure that packages these three facts together and proves the certificate is inhabited. The module proves nothing specific to shape memory alloys, because the definition of domain cost as J(m/e) does not tie m and e to any particular material property. The connection to nitinol is a research note recording where the idea was meant to go, not a result.

What this means in plain language: the framework offers a candidate formula for the hysteresis gap in shape memory alloys, and that formula lands in the observed range for nitinol. The gap between the intended application and the proved content is the gap between a hypothesis and a theorem. The general facts about the cost function are proved; the application to a specific alloy is not yet a proved theorem, because the module does not define what m and e are in terms of the alloy's physics.

THEOREM domainCost_at_eq · IndisputableMonolith/Materials/ShapeMemoryAlloyFromJCost.lean
theorem domainCost_at_eq (r : ℝ) (h : r ≠ 0) : domainCost r r = 0 := by
  unfold domainCost; rw [div_self h]; exact Jcost_unit0
THEOREM domainCost_nonneg · IndisputableMonolith/Materials/ShapeMemoryAlloyFromJCost.lean
theorem domainCost_nonneg (m e : ℝ) (hm : 0 < m) (he : 0 < e) : 0 ≤ domainCost m e := by
  unfold domainCost; exact Jcost_nonneg (div_pos hm he)
THEOREM canonicalThreshold_pos · IndisputableMonolith/Materials/ShapeMemoryAlloyFromJCost.lean
theorem canonicalThreshold_pos : 0 < canonicalThreshold := by
  unfold canonicalThreshold; linarith [phi_gt_onePointFive]
THEOREM cert_inhabited · IndisputableMonolith/Materials/ShapeMemoryAlloyFromJCost.lean
theorem cert_inhabited : Nonempty SMACert := ⟨cert⟩

What this page does not claim

The module does not prove that the hysteresis width of any real alloy equals J(phi) times its transformation temperature. The module does not define the quantities m and e in terms of the alloy's crystal structure or thermodynamics. The empirical agreement for nitinol is a consistency check, not a measured confirmation of the framework.

Verify this page

Every tagged claim above names its theorem. To check one yourself rather than trust this page, elaborate the source module with Lean 4 and audit its axiom basis:

$ lake env lean IndisputableMonolith/Materials/ShapeMemoryAlloyFromJCost.lean
expected axiom basis: [propext, Classical.choice, Quot.sound] (the Lean kernel's standard three; no RS-specific axioms)

A page whose claims cannot be reproduced this way does not ship. In production, every anchor links to the exact declaration in the public source release, and this block carries the build receipt for the page itself.

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