This page describes the physical and mechanical properties, applications, grades and types of products.
General
Precision alloys with special electric properties belong to a more general class of cryogenic materials. They have a certain set of electric properties under low temperatures (-269-+20 °С); they are applied in cryogenic instrument engineering and electrical machine-building for creating liquid helium level meters, temperature sensors and resistive strain sensors.
Nickel-molybdenum (Ni-Mo) with vanadium (V) and aluminum (Al) additives: NiMo23AlV
Iron-chromium-aluminium (Fe-Cr-Al) with molybdenum (Mo) and vanadium (V): 0Cr13AlV5VМo
Classification
By physical properties, the considered materials can be divided into 2 groups:
with a low regulated temperature coefficient of resistance (TCR);
superconductors (with a set temperature of superconducting transition (TK) and small TCR).
Table 1
Grade
General specification
Intended use
With a low regulated temperature coefficient of resistance
NiMo23AlV 0Cr13Al5VMo
Low-temperature coefficient of resistance (±2)-(±20)·10-6К-1 within interval T from -269 to 20 °С. High specific resistance (1.45-1.7 µΩ·m).
Sensitive girds of temperature-compensated low-temperature resistive strain sensors
Superconductors
70TiMo
TKsimilar to the temperature of liquid helium (from -268.6 to -268.4 °С), abrupt superconducting transition (transition width ≤ 0.2°С), change of resistance within T from -268 to 20 °С ≤ 10%
Liquid helium level meters
NbTiTs-VA
Critical current per unit of width of cold-rolled strip 20 microns thick and 90-100 mm wide not lower than (8.5-9.0)·104 А/m, superconducting transition 8.5-9.0 К, rupture strength 100-110 Н/mm2
Superconducting topologic generators of commutator switches in systems of input and output of superconductive magnet energy; cryogenic structures
35NbTi
Current critical density in transverse magnetic field 3.2·106 А/m under 4.2 К jK = (3-6)·104 А/cm2. Well-deformable, can be used for producing thin wire, strip, superconductive composition materials with a large number of conductors (up to 361)
Superconductive screens of the magnet field, conductors of superconductive magnet systems
Properties
NiMo23AlV and 0Cr13Al5VMo grades are peculiar for their low regulated temperature coefficient of resistance within T from -269 to 20 °С so as high specific resistance. Specifically, NiMo23AlV alloy has a regulated positive temperature coefficient of resistance and 0Cr13Al5VMo - regulated negative temperature coefficient of resistance.
The TK of T70TiMo grade based on Ti-Мо system is similar to the temperature of liquid helium (-269 °С) and low TCR in normal state. TK from 268.6 to 268.4 °С; transition width ΔTK ≤ 0.02°С, deviation of TK along the wire length ±0.1%; resistance within -268 to 20 °С ≤ 10 %, σB=980 MPa.
Grades
The main grades of precision alloys with high resistance are given in Classification section, Table 1. The chemical composition and other requirements towards them are regulated by GOST 10994-74.
Applications/drawbacks
The considered materials are applied under ultralow temperatures only as they can maintain their unique parameters in such conditions.
Cryogenic instrument engineering and machine engineering are the most popular industrial applications of precision alloys with special electric properties. They are used for producing liquid helium level meters, temperature sensors, sensitive grids of temperature-compensated low-temperature resistive strain sensors used for measuring static deformation under low temperatures.
Products
The materials with special electric properties for industrial use are produced in form of small wire - from 0.01 to 0.2 mm.