Pub Date : 2018-11-16DOI: 10.1201/9781351045636-140000437
M. Gasik, M. Gasik
In this article, an overview of aluminum reduction from oxides and other aluminum compounds is provided. Specific topical coverage addressed are: physical chemistry of aluminum reduction, smelting processes including: the Hall-Héroult Process, the ALCAN Process, the Alcoa process, the Elliot-Mitt Process, and others. In addition, direct reduction of aluminum alloys, and electrodes for aluminum production are discussed.
{"title":"Smelting of Aluminum","authors":"M. Gasik, M. Gasik","doi":"10.1201/9781351045636-140000437","DOIUrl":"https://doi.org/10.1201/9781351045636-140000437","url":null,"abstract":"In this article, an overview of aluminum reduction from oxides and other aluminum compounds is provided. Specific topical coverage addressed are: physical chemistry of aluminum reduction, smelting processes including: the Hall-Héroult Process, the ALCAN Process, the Alcoa process, the Elliot-Mitt Process, and others. In addition, direct reduction of aluminum alloys, and electrodes for aluminum production are discussed.","PeriodicalId":348912,"journal":{"name":"Encyclopedia of Aluminum and Its Alloys","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-11-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131232814","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2018-11-16DOI: 10.1201/9781351045636-140000389
M. Rhamdhani, G. Brooks, M. Dewan, B. Monaghan, L. Prentice
The production of Al from its ores at present relies on the Bayer (alumina production) and the Hall–Heroult (Al production) process. The cost associated with alumina production and apparent disadvantages of the Hall–Heroult process have led to intensive research to find alternative routes for Al production. The direct carbothermal reduction process has been thoroughly investigated as an alternative technique. Another alternative includes the indirect carbothermal reduction route where alumina (or aluminous ores) is first reduced to intermediate Al compounds before reduced further to Al. The present study reviews and provides systematic thermodynamic analyses of alternative Al production routes. In this paper, a comprehensive review of alternative Al production techniques focusing on the indirect carbothermal reduction routes is presented. These include carbochlorination, carbonitridation and carbosulphidation routes for the formation of intermediate Al compounds, followed by various Al extraction processes.
{"title":"Production Methods for Aluminum: Alternative","authors":"M. Rhamdhani, G. Brooks, M. Dewan, B. Monaghan, L. Prentice","doi":"10.1201/9781351045636-140000389","DOIUrl":"https://doi.org/10.1201/9781351045636-140000389","url":null,"abstract":"The production of Al from its ores at present relies on the Bayer (alumina production) and the Hall–Heroult (Al production) process. The cost associated with alumina production and apparent disadvantages of the Hall–Heroult process have led to intensive research to find alternative routes for Al production. The direct carbothermal reduction process has been thoroughly investigated as an alternative technique. Another alternative includes the indirect carbothermal reduction route where alumina (or aluminous ores) is first reduced to intermediate Al compounds before reduced further to Al. The present study reviews and provides systematic thermodynamic analyses of alternative Al production routes. In this paper, a comprehensive review of alternative Al production techniques focusing on the indirect carbothermal reduction routes is presented. These include carbochlorination, carbonitridation and carbosulphidation routes for the formation of intermediate Al compounds, followed by various Al extraction processes.","PeriodicalId":348912,"journal":{"name":"Encyclopedia of Aluminum and Its Alloys","volume":"8 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-11-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132354916","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2018-11-16DOI: 10.1201/9781351045636-140000224
J. Fiocchi, R. Casati, M. Vedani
Metal matrix nanocomposites are a novel class of materials, consisting of a metallic matrix reinforced by nanoparticles. They display interesting mechanical and functional properties, which can be carefully tailored and may be largely different than those of the base metal. Aluminum matrix nanocomposites have risen particular attention thanks to their low density and improved strength. Some issues in the production of nanocomposites are caused by the low wettability of nanoparticles; hence, innovative synthesis methods have been developed. In this work, the main production routes are reviewed; moreover, the strengthening mechanism acting in nanocomposites and the resulting mechanical properties are reported. Finally, the influence of reinforcement on precipitation processes in aluminum-based composites and some potential applications are described.
{"title":"Nanocomposites with Aluminum Matrix: Preparation and Properties","authors":"J. Fiocchi, R. Casati, M. Vedani","doi":"10.1201/9781351045636-140000224","DOIUrl":"https://doi.org/10.1201/9781351045636-140000224","url":null,"abstract":"Metal matrix nanocomposites are a novel class of materials, consisting of a metallic matrix reinforced by nanoparticles. They display interesting mechanical and functional properties, which can be carefully tailored and may be largely different than those of the base metal. Aluminum matrix nanocomposites have risen particular attention thanks to their low density and improved strength. Some issues in the production of nanocomposites are caused by the low wettability of nanoparticles; hence, innovative synthesis methods have been developed. In this work, the main production routes are reviewed; moreover, the strengthening mechanism acting in nanocomposites and the resulting mechanical properties are reported. Finally, the influence of reinforcement on precipitation processes in aluminum-based composites and some potential applications are described.","PeriodicalId":348912,"journal":{"name":"Encyclopedia of Aluminum and Its Alloys","volume":"33 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-11-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115779710","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2018-11-16DOI: 10.1201/9781351045636-140000285
J. Campbell
The Ten Rules are a checklist of the conditions necessary for the production of successful castings, particularly dealing with the metal quality, with a view to achieving a casting with minimal, preferably zero, faults. The first five Rules specify the conditions to avoid entrainment defects, particularly bifilms and bubbles. The remaining Rules deal with the provision of feeding, avoidance of convection, chemical segregation, and residual stress, and the provision of pickup locations for machining.
{"title":"Castings: Ten Rules for Good Castings","authors":"J. Campbell","doi":"10.1201/9781351045636-140000285","DOIUrl":"https://doi.org/10.1201/9781351045636-140000285","url":null,"abstract":"The Ten Rules are a checklist of the conditions necessary for the production of successful castings, particularly dealing with the metal quality, with a view to achieving a casting with minimal, preferably zero, faults. The first five Rules specify the conditions to avoid entrainment defects, particularly bifilms and bubbles. The remaining Rules deal with the provision of feeding, avoidance of convection, chemical segregation, and residual stress, and the provision of pickup locations for machining.","PeriodicalId":348912,"journal":{"name":"Encyclopedia of Aluminum and Its Alloys","volume":"285 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-11-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116107874","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2018-11-16DOI: 10.1201/9781351045636-140000237
C. Huitrón, E. Valdés, S. Valtierra, R. Colás
The effect that modification of cast Al-Si alloys exerts on the thermal and electrical conductivities is presented. The work was conducted by casting a series of samples in a rig that promotes unidirectional solidification to vary the level of microstructure refining, which was assessed by the secondary dendrite arm spacing. The alloys were prepared in a furnace and poured into the rig after adding different amounts of strontium to modify the aspect of the aluminum-silicon eutectic. Measurements were conducted on as-cast and heat-treated specimens. The electrical conductivity tests were referred to the International Annealed Copper Standard. Thermal conductivity of the different samples was obtained by comparing it with that of a high-purity aluminum sample. It was found that either value of conductivity depends on the degree of modification and by heat treating, whereas other microstructural parameters exert a secondary effect.
{"title":"Cast Al-Si-Cu Alloys: Effect of Modification on Thermal and Electrical Conductivities","authors":"C. Huitrón, E. Valdés, S. Valtierra, R. Colás","doi":"10.1201/9781351045636-140000237","DOIUrl":"https://doi.org/10.1201/9781351045636-140000237","url":null,"abstract":"The effect that modification of cast Al-Si alloys exerts on the thermal and electrical conductivities is presented. The work was conducted by casting a series of samples in a rig that promotes unidirectional solidification to vary the level of microstructure refining, which was assessed by the secondary dendrite arm spacing. The alloys were prepared in a furnace and poured into the rig after adding different amounts of strontium to modify the aspect of the aluminum-silicon eutectic. Measurements were conducted on as-cast and heat-treated specimens. The electrical conductivity tests were referred to the International Annealed Copper Standard. Thermal conductivity of the different samples was obtained by comparing it with that of a high-purity aluminum sample. It was found that either value of conductivity depends on the degree of modification and by heat treating, whereas other microstructural parameters exert a secondary effect.","PeriodicalId":348912,"journal":{"name":"Encyclopedia of Aluminum and Its Alloys","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-11-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122376916","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2018-11-16DOI: 10.1201/9781351045636-140000204
S. Murty, Sushant K. Manwatkar, P. Narayanan
{"title":"SEM Microstructures and Fractographs of Aluminum Alloys","authors":"S. Murty, Sushant K. Manwatkar, P. Narayanan","doi":"10.1201/9781351045636-140000204","DOIUrl":"https://doi.org/10.1201/9781351045636-140000204","url":null,"abstract":"","PeriodicalId":348912,"journal":{"name":"Encyclopedia of Aluminum and Its Alloys","volume":"39 8 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-11-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125290522","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2018-11-16DOI: 10.1201/9781351045636-140000337
B. Rivolta, R. Gerosa
The demand of alloys with high strength-to-density ratio is continuously increasing in the engineering world. Beside very expensive materials, such as the titanium alloys and the high strength reinforced polymers, the aluminum alloys represent an excellent alternative to satisfy the challenging requirements of many mechanical and aerospace applications. Among these alloys, the heat treatable grades are much appreciated for the possibility to increase the mechanical resistance significantly after solution treatment and aging. The former aims to create a supersaturated solution that is later modified during the latter by the formation of metastable precipitates involving all or some of the alloying elements. In the technical literature, it is well known that the corrosion resistance and the mechanical properties of these alloys, especially the 7xxx grades, strongly depend on the quenching conditions after the solution treatment. This phenomenon is known as “quench sensitivity.” The main aim of this entry is to discuss the influence of the cooling rate during quenching of different commercial aluminum alloys from mechanical and corrosion points of view. The influence of the rolling direction and of the alloy temper will be considered to focusing the attention on some experimental data obtained on the 7075 aluminum alloy.
{"title":"Quench Sensitivity of Aluminum Alloys","authors":"B. Rivolta, R. Gerosa","doi":"10.1201/9781351045636-140000337","DOIUrl":"https://doi.org/10.1201/9781351045636-140000337","url":null,"abstract":"The demand of alloys with high strength-to-density ratio is continuously increasing in the engineering world. Beside very expensive materials, such as the titanium alloys and the high strength reinforced polymers, the aluminum alloys represent an excellent alternative to satisfy the challenging requirements of many mechanical and aerospace applications. Among these alloys, the heat treatable grades are much appreciated for the possibility to increase the mechanical resistance significantly after solution treatment and aging. The former aims to create a supersaturated solution that is later modified during the latter by the formation of metastable precipitates involving all or some of the alloying elements. In the technical literature, it is well known that the corrosion resistance and the mechanical properties of these alloys, especially the 7xxx grades, strongly depend on the quenching conditions after the solution treatment. This phenomenon is known as “quench sensitivity.” The main aim of this entry is to discuss the influence of the cooling rate during quenching of different commercial aluminum alloys from mechanical and corrosion points of view. The influence of the rolling direction and of the alloy temper will be considered to focusing the attention on some experimental data obtained on the 7075 aluminum alloy.","PeriodicalId":348912,"journal":{"name":"Encyclopedia of Aluminum and Its Alloys","volume":"258 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-11-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125810063","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2018-11-16DOI: 10.1201/9781351045636-120052503
D. Dışpınar
It is well known that the reaction of liquid aluminum with the moisture in the environment results in two products: aluminum oxide and hydrogen gas that dissolves in aluminum. Both of these products are considered to be detrimental to the properties of aluminum alloys. Therefore, test equipment has been developed to check the levels of these defects in the melt. Many of these involve expensive and consumable tools. In addition, an experienced personnel may be required to interpret the results. Nonetheless, aluminum oxide is harmless as long as it remains on the surface. The problem begins when this oxide is entrained into the liquid aluminum such as turbulence during transfer or mold filling in a non-optimized design. This can only happen by folding of the oxide. During this action, rough surface of the oxides comes in contact to form no bonds. These defects are known as bifilms that have certain characteristics. First, they act as cracks in the cast parts since they are oxides. It is important to note that aluminum oxide has thin amorphous oxide (known as young oxides) and thick crystalline oxide (γ-Al2O3) that may be formed in a casting operation. Second, almost zero force is required to open these bifilms due to the unbonded folded oxide skins. Thus, these defects can easily form porosity by unravelling during solidification shrinkage. On the other hand, the formation of porosity by hydrogen is practically impossible. Theoretically, hydrogen has high solubility in the liquid but it has significantly low solubility in solid aluminum. Thus, it is suspected that hydrogen is rejected from the solidification front to form hydrogen gas and porosity. However, the hydrogen atom has the smallest atomic radii and high diffusibility. Therefore, segregation of hydrogen in front of the growing solid is difficult. In addition, the energy required for hydrogen atoms to segregate and form hydrogen gas molecule is around 30,000 atm. Under these conditions, porosity formation by hydrogen is not likely to be achieved. Hydrogen probably stays in a supersaturated state or diffuses homogeneously through the cast part. The effect of hydrogen can only be seen when it can diffuse into the unbonded gap between the bifilms to open them up to aid the unravelling of bifilms to form porosity. This phenomenon can be easily detected by a very simple test called reduced pressure test. When a sample is solidified under vacuum, the bifilms start to open up. Since all porosity is formed by bifilms, the cross section of the sample solidified under vacuum can be analyzed by means of image analysis software. The sum of maximum length of pores can be measured as an indication of melt quality. Since bifilms are the most detrimental defects, this value is called “bifilm index” given in millimetres, which makes this test the only test that can quantify aluminum melt quality in such detail including both the effects of bifilms and hydrogen together. Several Al-Si alloys were used at var
{"title":"Melt Quality Assessment","authors":"D. Dışpınar","doi":"10.1201/9781351045636-120052503","DOIUrl":"https://doi.org/10.1201/9781351045636-120052503","url":null,"abstract":"It is well known that the reaction of liquid aluminum with the moisture in the environment results in two products: aluminum oxide and hydrogen gas that dissolves in aluminum. Both of these products are considered to be detrimental to the properties of aluminum alloys. Therefore, test equipment has been developed to check the levels of these defects in the melt. Many of these involve expensive and consumable tools. In addition, an experienced personnel may be required to interpret the results. Nonetheless, aluminum oxide is harmless as long as it remains on the surface. The problem begins when this oxide is entrained into the liquid aluminum such as turbulence during transfer or mold filling in a non-optimized design. This can only happen by folding of the oxide. During this action, rough surface of the oxides comes in contact to form no bonds. These defects are known as bifilms that have certain characteristics. First, they act as cracks in the cast parts since they are oxides. It is important to note that aluminum oxide has thin amorphous oxide (known as young oxides) and thick crystalline oxide (γ-Al2O3) that may be formed in a casting operation. Second, almost zero force is required to open these bifilms due to the unbonded folded oxide skins. Thus, these defects can easily form porosity by unravelling during solidification shrinkage. On the other hand, the formation of porosity by hydrogen is practically impossible. Theoretically, hydrogen has high solubility in the liquid but it has significantly low solubility in solid aluminum. Thus, it is suspected that hydrogen is rejected from the solidification front to form hydrogen gas and porosity. However, the hydrogen atom has the smallest atomic radii and high diffusibility. Therefore, segregation of hydrogen in front of the growing solid is difficult. In addition, the energy required for hydrogen atoms to segregate and form hydrogen gas molecule is around 30,000 atm. Under these conditions, porosity formation by hydrogen is not likely to be achieved. Hydrogen probably stays in a supersaturated state or diffuses homogeneously through the cast part. The effect of hydrogen can only be seen when it can diffuse into the unbonded gap between the bifilms to open them up to aid the unravelling of bifilms to form porosity. This phenomenon can be easily detected by a very simple test called reduced pressure test. When a sample is solidified under vacuum, the bifilms start to open up. Since all porosity is formed by bifilms, the cross section of the sample solidified under vacuum can be analyzed by means of image analysis software. The sum of maximum length of pores can be measured as an indication of melt quality. Since bifilms are the most detrimental defects, this value is called “bifilm index” given in millimetres, which makes this test the only test that can quantify aluminum melt quality in such detail including both the effects of bifilms and hydrogen together. Several Al-Si alloys were used at var","PeriodicalId":348912,"journal":{"name":"Encyclopedia of Aluminum and Its Alloys","volume":"30 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-11-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116708553","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2018-11-16DOI: 10.1201/9781351045636-140000387
X. Qiao, N. Gao, M. Starink
This paper presents a model which quantitatively predicts grain refinement and strength/hardness of Al alloys after very high levels of cold deformation through processes including cold rolling, equal channel angular pressing (ECAP), multiple forging (MF), accumulative rolling bonding (ARB) and embossing. The model deals with materials in which plastic deformation is exclusively due to dislocation movement, which is in good approximation the case for aluminium alloys. In the early stages of deformation, the generated dislocations are stored in grains and contribute to overall strength. With increase in strain, excess dislocations form and/or move to new cell walls/grain boundaries and grains are refined. We examine this model using both our own data as well as the data in the literature. It is shown that grain size and strength/hardness are predicted to a good accuracy.
{"title":"Grain Refinement and Strengthening of Aluminum Alloys: Cold Severe Plastic Deformation Model","authors":"X. Qiao, N. Gao, M. Starink","doi":"10.1201/9781351045636-140000387","DOIUrl":"https://doi.org/10.1201/9781351045636-140000387","url":null,"abstract":"This paper presents a model which quantitatively predicts grain refinement and strength/hardness of Al alloys after very high levels of cold deformation through processes including cold rolling, equal channel angular pressing (ECAP), multiple forging (MF), accumulative rolling bonding (ARB) and embossing. The model deals with materials in which plastic deformation is exclusively due to dislocation movement, which is in good approximation the case for aluminium alloys. In the early stages of deformation, the generated dislocations are stored in grains and contribute to overall strength. With increase in strain, excess dislocations form and/or move to new cell walls/grain boundaries and grains are refined. We examine this model using both our own data as well as the data in the literature. It is shown that grain size and strength/hardness are predicted to a good accuracy.","PeriodicalId":348912,"journal":{"name":"Encyclopedia of Aluminum and Its Alloys","volume":"32 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-11-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116977212","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2018-11-16DOI: 10.1201/9781351045636-140000202
Mitja Petri, J. Medved, S. Kastelic, M. Vončina, P. Mrvar
The aim of this paper is to explain the electrical resistivity change during solidification and connect it with the thermal analysis and solidification course. The problem at conducting the “in situ” measurement by four-point technique is the electrode material, which often oxidizes during measurements causing high contact resistance and providing incorrect results. Various materials were tested and aluminum electrodes chosen. The advantage of aluminum electrodes is that they melt within the specimen immediately after being poured and cause no interface resulting with any contact resistance. Pure aluminum, hypoeutectic alloy AlSi7Mg, and eutectic AlSi12 alloys were tested. Resistivity of Al–Si alloys is increasing with Si content. Grain refinement and modification of βSi were employed. Grain refinement has any effect on electrical resistivity. Modification of βSi phase causes decrease of electrical resistivity. The electrical resistivity curves give information similar as cooling curves from thermal analysis measurements.
{"title":"Electrical Resistivity of Al-Cast Alloys in the Range of Solidification","authors":"Mitja Petri, J. Medved, S. Kastelic, M. Vončina, P. Mrvar","doi":"10.1201/9781351045636-140000202","DOIUrl":"https://doi.org/10.1201/9781351045636-140000202","url":null,"abstract":"The aim of this paper is to explain the electrical resistivity change during solidification and connect it with the thermal analysis and solidification course. The problem at conducting the “in situ” measurement by four-point technique is the electrode material, which often oxidizes during measurements causing high contact resistance and providing incorrect results. Various materials were tested and aluminum electrodes chosen. The advantage of aluminum electrodes is that they melt within the specimen immediately after being poured and cause no interface resulting with any contact resistance. Pure aluminum, hypoeutectic alloy AlSi7Mg, and eutectic AlSi12 alloys were tested. Resistivity of Al–Si alloys is increasing with Si content. Grain refinement and modification of βSi were employed. Grain refinement has any effect on electrical resistivity. Modification of βSi phase causes decrease of electrical resistivity. The electrical resistivity curves give information similar as cooling curves from thermal analysis measurements.","PeriodicalId":348912,"journal":{"name":"Encyclopedia of Aluminum and Its Alloys","volume":"34 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-11-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124384596","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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