Metals & Alloys

  • Where is the eutectic melting temperature of the metal alloy?
  • How can one precisely characterize the shape-memory alloy?
  • At what temperature does oxidation of the metal surface begin?
  • How does the specific heat change with increasing temperature?

These or similar questions can be answered with modern thermoanalytical measuring techniques.

Specific heat, extension coefficient, melting and solidification reactions and characteristic thermal effects also under corrosive conditions may possibly be analytical goals for your applications.

Recommended literature:

Recommended literature:

Scientific Publications

Scientific Publications

Further scientific publications are to be found HERE.

Detailed Insight Into the World of Thermal Analysis

Detailed Insight Into the World of Thermal Analysis

Melting, crystallization, glass transition, secondary phase transition, and specific heat are important chemical properties for metals and alloys that are measured with the DSC or STA. Besides these, the influence of corrosion, oxidation or reduction as well as magnetic transitions and thermostability can also be determined.

With dilatometers, the coefficient of thermal expansion can be precisely measured; DMA determines practice-relevant values for the modulus of elasticity and the damping behavior of composites.

With LFA, the temperature and thermal conductivity of metals and their melts can also be investigated.

Some Application Examples

Some Application Examples

Melting Point Determination on Palladium

The largest use of palladium (Pd) today is in catalytic converters. However, it is also used in e.g., dentistry, watch making, blood sugar test strips, aircraft spark plugs and in the production of surgical instruments and electrical contacts. Palladium shows no reaction with oxygen at normal temperature although when heated to 800°C in air will produce a layer of palladium(II) oxide (PdO). This plot exhibits the STA measurement on Pd up to a sample temperature of 1600°C under argon atmosphere. The DSC curve (blue) shows the melting with an enthalpy of 158 J/g (blue curve, DSC) at 1554°C (onset temperature). Both values correspond very well with literature data (< 1%) for pure Pd. Before and after melting no mass loss occurred (green curve); this confirms the high purity of the metal as well as the vacuum-tightness of the STA 449 F5 Jupiter®®.

STA measurement on a Pd sample (44.33 mg) at a heating rate of 20 K/minSTA measurement on a Pd sample (44.33 mg) at a heating rate of 20 K/min

Seebeck Coefficient and Electrical Conductivity of PbTe

Lead telluride has good performance as a thermoelectric material, partly due to the low thermal conductivity and partly due to its electrical properties. This plots exhibits the Seebeck coefficient (green curve) and electrical conductivity (blue curve) between room temperature and 250°C. The dotted green line represents the PTB1)-certified values. A good correlation can be observed indicating the reliability of the system.

1) Physikalisch-Technische Bundesanstalt, Braunschweig

Seebeck coefficient and electrical conductivity of PbTeSeebeck coefficient and electrical conductivity of PbTe

Volumetric Expansion of an Aluminum Alloy into the Melt

The behavior of an aluminumbased alloy during heating is illustrated here. Displayed are the volumetric expansion (dV/V0, black) and the density change (red) which can both be calculated from the measured thermal expansion data by using the NETZSCH Density Determination software.

After an initial linear expansion the aluminum alloy starts to melt at 559°C (extrapolated onset temperature of the c-DTA® signal in dashed blue). For realizing such an experiment, a special container (here alumina, see photo) is necessary.

During melting a strong expansion occurs representing the mushy region in which liquid and solid state are present together. Above 622°C, the entire sample is molten. While the volume increases, the initial density drops down for about 10% (from 2.66 g/cm3 to 2.40 g/cm3) until the end of the measurement.The c-DTA® curve (blue) clearly shows the melting range by endothermal effects.

Thermal behavior of an aluminum-based alloyThermal behavior of an aluminum-based alloy, heating rate: 5 K/min, He atmosphere, constant contact force: 250 mN, alumina sample holder, alumina container. Displayed are the volumetric expansion (black solid line), the curve of the calculated density change (red solid line) as well as the c-DTA® curve (blue dashed line).