Observation of a continuous phase transition in a shape-memory alloy.
Elastic neutron-scattering, inelastic x-ray scattering, specific-heat, and pressure-dependent electrical transport measurements have been made on single crystals of AuZn and Au0.52Zn0.48. Elastic neutron scattering detects new commensurate Bragg peaks (modulation) appearing at Q =(1.33,0.67,0) at temperatures corresponding to each sample's transition temperature (TM = 64 and 45 K, respectively). Although the new Bragg peaks appear in a discontinuous manner in the Au0.52Zn0.48 sample, they appear in a continuous manner in AuZn. Surprising us, the temperature dependence of the AuZn Bragg peak intensity and the specific-heat jump near TM are in favorable accord with a continuous transition. A fit to the pressure dependence of TM suggests the presence of a critical end point in the AuZn phase diagram located at TM* = 2.7 K and p* = 3.1 GPa.
Lashley
J C
JC
Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA.
Shapiro
S M
SM
Winn
B L
BL
Opeil
C P
CP
Manley
M E
ME
Alatas
A
A
Ratcliff
W
W
Park
T
T
Fisher
R A
RA
Mihaila
B
B
Riseborough
P
P
Salje
E K H
EK
Smith
J L
JL
D001672:Biocompatible Materials / Q000737:chemistry; D006047:Gold Alloys / Q000737:chemistry*; D033363:Neutron Diffraction; D013696:Temperature; D013816:Thermodynamics; D014961:X-Ray Diffraction; D015032:Zinc / Q000737:chemistry*
D001672:Biocompatible Materials; D006047:Gold Alloys; D015032:Zinc