Electrical Resistivity Of Alloys Research Articles

Effect of different quenching holding times on microstructure, texture and electrical resistivity of NiCrAlFe alloy

Quenching treatment can provide microstructure for subsequent tempering treatment in the production process of NiCrAlFe precision resistance alloy. However, the recrystallization texture formed during quenching will be inherited into the tempered alloy, causing anisotropy of resistance and affecting the final performance of precision resistors. In order to investigate the evolution of the texture and its influence on the anisotropy of resistance, the effect of various quenching holding times on the alloy were studied. The results indicate that certain rolling deformation texture is gradually transformed into recrystallization texture and the texture intensity decreases significantly during the holding process. At the same time, the formation of a large number of twins promotes the formation of Brass-R {111}<112> texture at twin boundaries. The electrical resistivity of the alloy changes from 1.360 μΩ·m to 1.427 μΩ·m, and it shows an increasing trend with the holding time. The large number of supersaturated vacancies generated by quenching is the main reason for the increase in alloy electrical resistivity, but there is no correlation between the orientation density of texture and the electrical resistivity, however the type and intensity of textures exhibit significant influence on the anisotropy of the electrical resistivity. The electrical resistivity of direction rolling, direction 45°, and direction 65° are mainly influenced by Goss {110}<001> texture, Goss {110}<001> texture and Brass-R {111}<112> texture, and S {123}<634> texture and R {124}<211> texture, respectively.

Effects of heat treatment temperatures on phase transformation, thermodynamical parameters, crystal microstructure, and electrical resistivity of NiTiV shape memory alloy

Changing physical property of NiTi shape memory alloy by adding new element and heat treatment technique has become interesting in the last decades. In this study, equiatomic NiTi alloy was doped by 1 and 5 atomic percentages of vanadium element. For each case, heat treatment was accomplished for 873, 973, 1073, and 1173 K, and its effect on phase transformation temperatures was analyzed by differential scanning calorimetry. Crystal structure and chemical compound found in XRD pattern showed the different situation for each case, e.g., TiO2 appeared in heat-treated samples, whereby the intensity of peaks varied by changing the temperature of heat treatment. In NiTi–5V alloy, each enthalpy, entropy, Gibbs free energy, and elastic energy were decreased by increasing heat treatment temperature, while grain size of the alloy extended with respect to non-heat-treated sample. Electrical resistivity of the alloys was measured as a function of temperature, which was increased by increasing vanadium composition and heat treatment temperature.

Effect of addition of Cu on the properties of eutectic Sn-Bi solder alloy

Abstract The present work reports the effect of Cu addition on the melting point, hardness and electrical resistivity of Sn-57 wt.% Bi eutectic solder alloy. Both binary eutectic Sn-57 wt.% Bi and ternary Sn-(57-x)Bi-xCu (x = 0.1, 0.3, 0.5, 0.7 and 1 wt.%) alloys containing various amounts of Cu were developed by melting casting route. The microstructure of the various solder alloys was analyzed using an optical microscope and a SEM. The variation in melting point, hardness and electrical resistivity of the Sn-Bi eutectic solder alloys with the addition of Cu was determined. The melting point of the eutectic Sn-Bi solder alloy was found to decrease up to the addition of 0.7 wt.% Cu. However, further addition of Cu led to an increase in the melting point of the alloy. Addition of Cu led to an increase in the hardness of the eutectic Sn-Bi solder alloy whereas the electrical resistivity of this alloy was found to increase up to the addition of 0.7 wt.% of Cu beyond which a decrease in the electrical resistivity was observed. A change in the microstructure of the solder alloy was observed when it was reheated above the melting temperature.

Structure and Magnetic Properties of Fe-Cu-Nb-Si-B with Various Niobium Concentration

The microrelief of the contact, free sides and cuts of three metal alloys with various niobium contents were studied. It is shown that samples with high niobium content are X-ray amorphous, the alloys FeCu1Si16B6, FeCu1Nb3Si16B6are characterized by an amorphous-crystalline structure. The change in the magnetic characteristics and electrical resistance of alloys in the course of thermomagnetic annealing is studied. It is shown that an increase in the Nb content in an alloy increases its temperature stability and the temperature of the onset of crystallization processes.

Structure and Thermoelastic Martensitic Transformations in Ternary Ni–Ti–Zr Alloys with High-Temperature Shape Memory Effects

X-ray diffraction analysis and transmission electron and scanning electron microscopies were used to study the effect of alloying with zirconium (0–20 at %) on the phase composition and structural and morphological features of thermoelastic martensitic transformations in ternary Ni–Ti–Zr alloys. The electrical resistivity of alloys has been measured in a wide range of temperatures, the critical temperatures have been determined, and a complete diagram of the high-temperature thermoelastic forward and reverse martensitic transformations B2 ↔ B19' occurring with a hysteresis in the range of 32–50 K has been constructed based on XRD data. The intercritical range of the temperatures of transformations increases as the zirconium content increases within the indicated limits. The lattice parameters of the monoclinic crystal lattice of the B19' martensite have been measured at room temperature. The twinning types most frequently observed in B19' martensite have been found as follows: I-(011), $$\left( {11\;\bar 1} \right)$$ and (001), II-(011).

The Change of Electrical Resistivity Accourding to Different Quench Techniques in Copper-Manganese Alloy

Accepted: 29.06.2016 It is known that copper has electrical and thermal conductivity. Therefore Cu-based alloys are used in technological and engineering applications. This paper is aimed at studying influence of various heat treatment on electrical resistivity properties of samples from binary Cu-Mn alloy. The chemical composition of the alloy was found to be Cu75.8-Mn24.2 (wt.%) by using energy dispersive x-ray analysis (EDAX) technique. Electrical resistivity is a fundamental property of many materials. Hence, it is a key physical property of all materials. The electrical properties of binary Cu-Mn system performed by using a standard four-point probe D.C. method A Keithley 2400 sourcemeter. The resistivity measurements are carried out in the temperature range from 50 to 300 °C during heating. In the measurements, important properties were observed. The values of electrical resistivity of alloy was determined as a function of temperature. The specific resistivity changed linearly with the temperature. The differents showed the resistivity as a function of quenching temperature. The relative values of electrical resistivity also increased with increasing rate of quenching.

The Effects of Solid-Solution on Properties and Microstructure of 6063 Aluminum Alloy

The solution treatment of 6063 aluminum alloy was carried out and the influences of solution process on microstructure, strength, hardness, and electrical resistivity of 6063 aluminum alloy was analyzed. The result shows that the suitable solution treatment can improve alloy solution-degree fully, meanwhile the changes of electrical resistivity of alloy tend to be balanced. The suitable solution process for 6063 aluminum alloy is solution-treated at 520°C for 3.5h, and the strength and hardness of alloy can be enhanced extremely after aging-treatment at 200°C for 5h.

Effects of growth rate on the physical and mechanical properties of Sn-3.7Ag-0.9Zn eutectic alloy

Sn-3.7wt.%Ag-0.9wt.%Zn alloy was directionally solidified upward under different conditions, with different growth rates (V = 3.38 - 220.12 µm/s) at a constant temperature gradient (G = 4.33 K/mm) and with different temperature gradients (G = 4.33 -12.41 K/mm) at a constant growth rate (V = 11.52 µm/s) by using a Bridgman-type directional solidification furnace. The microstructure was observed to be a rod Ag 3Sn structure in the matrix of β-Sn from the directionally solidified Sn-3.7wt.%Ag-0.9wt.%Zn samples. The microhardness, tensile strength and electrical resistivity of alloy were measured from directionally solidified samples. The dependency of the microhardness, tensile strength and electrical resistivity on the solidification parameters for directionally solidified Sn-Ag-Zn eutectic alloy was investigated and the relationships between them were experimentally obtained by using regression analysis. The results obtained in the present work were compared with the previous similar experimental results.

Temperature dependence of electrical resistance of alloys caused by dynamic and static disorders

The results are presented of the experimental (in situ) measurements of electrical resistance and thermal expansion of electron compositions and their mechanical copper- and zinc-based mixtures, as well as of stainless steels within the temperature range of 300–1000 K. From the correlation analysis of these properties, the thermal deformation of the atomic lattice is shown to play the key role in formation of the electron scattering cross section. The role of the static disorder in the scattering cross section formation in alloys becomes noticeable for lattices with a high atom packing density.

Theory of the residual electrical resistivity of binary actinide alloys

A system of self-consistent equations has been proposed for the coherent potential approximation of the multiband conductivity model for the case of conduction electron scattering from chaotic electric fields of ions of disordered binary alloy components at zero temperature. It has been qualitatively demonstrated that the deviation of the concentration dependence of the residual electrical resistivity of actinide alloys with multiband conductivity from the Nordheim rule is caused by the explicit dependence of the electrical resistivity of the alloy on the magnitude and sign of the real part of the Green’s function at the Fermi level. The derived system of equations for the multiband coherent potential approximation has been used to calculate the concentration dependence of the density of states and the residual electrical resistivity of the alloys of neptunium and plutonium. The results of the calculations have been compared with the available experimental data.

Effect of Hydrogen Absorption on the Electrical Resistance of Melt-Spun Mg-Pd and Mg-Ni-Pd Amorphous Alloys

The Mg100−xPdx (x = 10, 20 and 30), Mg80Ni20−yPdy (y = 5 and 10) and Mg75Ni20Pd5 amorphous alloys were prepared by the single-roller melt-spinning technique. The electrical resistance was measured during electrochemical hydrogen charging in 6N KOH solution. The Mg90Pd10 amorphous alloy shows larger increase in the electrical resistance by hydrogen absorption than any other alloys prepared in this study. Moreover, the electrical resistance of those alloys was also measured in hydrogen-dissolved water prepared by the bubbling method. As a result, it was found that the electrical resistance increases with increasing immersion time and that the increase amount of the electrical resistance is dependent on the alloy composition. The increase amount of the electrical resistance of the Mg90Pd10 amorphous alloy is much larger than those of other alloys prepared in this work. The increase amount of the electrical resistance of the Mg90Pd10 amorphous alloy after immersion in hydrogen-dissolved water for 300 s is dependent on the concentration of hydrogen in water, and it increases with increasing hydrogen concentration in water. From these results, it is confirmed that hydrogen absorption has a great influence on the electrical resistance of the Mg-based amorphous alloys and that the sensitivity to hydrogen can change largely depending on the alloy composition even in the similar alloy systems.

Electrical and Magnetic Study of Bulk Amorphous Alloys Fe-Al-Ga-P-B-Si

Bulk amorphous alloys Fe-Al-Ga-P-B-Si were prepared by a single-roller melt spinning method. Electrical resistivity of alloys is of the order of 200 μΩcm. The structural and magnetic components of resistivity are separated. The anomalous rise of resistivity during crystallization observed in Fe-Al-Ga-P-B-Si alloys with higher Si content is related to the precipitation of high resistivity crystalline phases. The strong exchange interaction is revealed by the Curie temperatures reaching 640 K. The room temperature values of the effective magnetic moment vary between 1.79 and 1.83 μB depending weakly on alloy composition. The AC hysteresis loops were recorded in magnetic fields up to 50 A/cm and frequencies between 10 Hz to 400 kHz. The frequency variation of power losses shows that high resistivity reduces eddy current losses.

Anomalous behavior of the electrical resistivity in alloys near the PrNi 5.0 composition

The phase relationships near the PrNi 5 composition at high temperatures (above 1000 °C) were determined. At 1000 °C a solid solution region, about 1 at.% wide, exists from PrNi 5.0 to PrNi 5.2. The electrical resistivity was measured for six alloys with compositions between PrNi 4.6 and PrNi 5.2 from room temperature to 4.2 K. Thermal cycling of the alloy leads to a resistance increase of 10%–20% over the initial room temperature value. Metallographic studies confirmed that this increase was due to crack formation upon cooling. The results obtained in this study suggest that PrNi 4.8 and PrNi 4.9 would be the best compositions of the six samples studied for use as a nuclear refrigerant to reach millikelvin temperatures.

Electrical properties and structure of alloys of the Cu?In?Al system

1. With an atomic fraction of copper less than 67–68%, inclusions of pure indium are observed in the alloy. 2. In alloys with atomic fractions of indium less than 15% there is a series of reversible phase reactions. At 740°C β+δ⇆γ is observed, at 675°C α+δ⇆β2+δ transformation is observed, and close to 560°C eutectoid α+γ2⇆β1+α -transformation occurs. 3. Anomalies at 160°C in the temperature dependence curves for internal friction and electrical resistivity in alloys with an atomic fraction of indium greater than 15% are due to a change in the aggregated condition of inclusions. 4. An increase in the content of indium inclusions leads to deterioration of test alloy properties, in particular microhardness is H 1200–1300 (for alloy with an atomic fraction of indium of 25%), which is typical for brittle materials.

Structural stability of heat-resistant nickel alloys at high temperatures

1. The electrical resistance of heat-resistant nickel alloys in the temperature range of dissolution of the γ′-phase is determined primarily by the volume share of γ′-phase and its specific electrical resistance. In dissolution of the γ′-phase the specific electrical resistance of the alloys drops. 2. The temperature of the start of dissolution of the γ′-phase does not depend upon the change in content of the alloy elements and is 855±10°C. An increase in the alloy of the aluminum, titanium, and niobium contents leads to an increase in the temperature of complete dissolution of the γ′-phase, while a change in the chronium, cobalt, and molybdenum contents has practically no influence on it.

Electrical resistivity of alloys in the systems Cu?Mn?Ge, Cu?Mn?Sn, and Cu?Ge?Sn

Electrical resistivity of alloys in the systems Cu?Mn?Ge, Cu?Mn?Sn, and Cu?Ge?Sn

Temperature dependence of the electrical resistivity of alloys with Guinier-Preston zones

The influence of the measuring temperature TM on the residual resistivity Delta rho has been investigated in four alloys (Al-Ag, Al-Cu, Al-Zn and Cu-Be) where Guinier-Preston zone information leads to the time dependence of the resistivity showing a maximum during ageing. In the two alloys where spherical precipitates form (Al-Ag and Al-Zn), the influence of Tm on Delta rho seems to be negligible while the presence of monolayer plate-like particles (in Al-Cu and Cu-Be) induces a higher peak occurring at a later ageing time when the measuring temperature is raised. These experimental results are analysed by using the most recent theoretical models and the effects on Delta rho of the deformations induced by the precipitates are investigated.

Effect of heat treatment and deviation from stoichiometry on the structure and physical properties of titanium nickelide

1. Alloys containing 48–50 at. % Ni are not hardened from 980°, while β phase is formed after quenching of alloys with >50.8% Ni. 2. The properties of quenched alloys do not change as the result of holding at room temperature for as long as 5500 h. 3. Prolonged annealing at 500–450° leads to formation of finely dispersed phase and lower electrical resistivity of alloys with 50.2–51.8 at. % Ni. Alloys with 49.8–50.2 at. % Ni are insensitive to all the heat treatments tested.

Ageing behaviour of cast Pb—Sb battery grids

The behaviour` of cast Pb—4%Sb and Pb—6%Sb battery grids has been studied by following the changes with time of tensile properties, microhardness, and electrical resistivity in alloys cooled at different rates after casting. The effects of the different cooling conditions on ageing have been explained by the resulting distribution of antimony in the α portion of the dendrites, which has been measured by an electron microprobe procedure, and compared with theoretical distributions calculated from non-equilibrium cooling conditions. The effects of the different variables on the expected behaviour of the grids are discussed.

Equilibrium values of short-range order in gold-silver and gold-palladium-alloys

In previous papers the influence of quenching and annealing treatments on the electrical resistivity of alloys has been measured and interpreted as influence of the quenched-in vacancies upon kinetics of short-range order formation. In the present paper it is investigated under which conditions values corresponding to the equilibrium of short-range order can be found. It has been shown that such equilibrium values can be obtained only in a temperature range limited to both sides and that this range can be checked and extended by suitable combinations of heat treatments. The resistivity values measured for Au-Ag and Au-Pd alloys are discussed from this point of view.