rajpurkar/squad huggingface dataset:
Title: Alloy

An alloy is a mixture of either pure or fairly pure chemical elements, which forms an impure substance (admixture) that retains the characteristics of a metal. An alloy is distinct from an impure metal, such as wrought iron, in that, with an alloy, the added impurities are usually desirable and will typically have some useful benefit. Alloys are made by mixing two or more elements; at least one of which being a metal. This is usually called the primary metal or the base metal, and the name of this metal may also be the name of the alloy. The other constituents may or may not be metals but, when mixed with the molten base, they will be soluble, dissolving into the mixture.

Question: What kind of substance is an alloy?
Answer: impure

Question: What happens when an alloy is mixed with a molten base?
Answer: they will be soluble, dissolving into the mixture

Question: What is an alloy composed of?
Answer: two or more elements

Question: What other metal is impure like alloy?
Answer: wrought iron
Title: Alloy

When the alloy cools and solidifies (crystallizes), its mechanical properties will often be quite different from those of its individual constituents. A metal that is normally very soft and malleable, such as aluminium, can be altered by alloying it with another soft metal, like copper. Although both metals are very soft and ductile, the resulting aluminium alloy will be much harder and stronger. Adding a small amount of non-metallic carbon to iron produces an alloy called steel. Due to its very-high strength and toughness (which is much higher than pure iron), and its ability to be greatly altered by heat treatment, steel is one of the most common alloys in modern use. By adding chromium to steel, its resistance to corrosion can be enhanced, creating stainless steel, while adding silicon will alter its electrical characteristics, producing silicon steel.

Question: How is steel produced?
Answer: Adding a small amount of non-metallic carbon to iron

Question: What kind of metal is soft like copper?
Answer: aluminium

Question: What can be added to steel to enhance is corrosion resistance?
Answer: chromium

Question: What is superior to pure iron?
Answer: steel

Question: What is another word for when alloys solidify?
Answer: crystallizes
Title: Alloy

Although the elements usually must be soluble in the liquid state, they may not always be soluble in the solid state. If the metals remain soluble when solid, the alloy forms a solid solution, becoming a homogeneous structure consisting of identical crystals, called a phase. If the mixture cools and the constituents become insoluble, they may separate to form two or more different types of crystals, creating a heterogeneous microstructure of different phases. However, in other alloys, the insoluble elements may not separate until after crystallization occurs. These alloys are called intermetallic alloys because, if cooled very quickly, they first crystallize as a homogeneous phase, but they are supersaturated with the secondary constituents. As time passes, the atoms of these supersaturated alloys separate within the crystals, forming intermetallic phases that serve to reinforce the crystals internally.

Question: What causes an alloy to form a solid solution?
Answer: If the metals remain soluble when solid

Question: What is the purpose of intermetallic phases?
Answer: to reinforce the crystals internally

Question: What are alloys called when the insoluble elements don't separate until after crystallization occurs?
Answer: intermetallic alloys
Title: Alloy

Some alloys occur naturally, such as electrum, which is an alloy that is native to Earth, consisting of silver and gold. Meteorites are sometimes made of naturally occurring alloys of iron and nickel, but are not native to the Earth. One of the first alloys made by humans was bronze, which is made by mixing the metals tin and copper. Bronze was an extremely useful alloy to the ancients, because it is much stronger and harder than either of its components. Steel was another common alloy. However, in ancient times, it could only be created as an accidental byproduct from the heating of iron ore in fires (smelting) during the manufacture of iron. Other ancient alloys include pewter, brass and pig iron. In the modern age, steel can be created in many forms. Carbon steel can be made by varying only the carbon content, producing soft alloys like mild steel or hard alloys like spring steel. Alloy steels can be made by adding other elements, such as molybdenum, vanadium or nickel, resulting in alloys such as high-speed steel or tool steel. Small amounts of manganese are usually alloyed with most modern-steels because of its ability to remove unwanted impurities, like phosphorus, sulfur and oxygen, which can have detrimental effects on the alloy. However, most alloys were not created until the 1900s, such as various aluminium, titanium, nickel, and magnesium alloys. Some modern superalloys, such as incoloy, inconel, and hastelloy, may consist of a multitude of different components.

Question: What is electrum made of?
Answer: silver and gold

Question: What alloy is formed naturally? 
Answer: electrum

Question: Which was on of the first alloys made by humans?
Answer: bronze

Question: What metal is made by combining tin and copper?
Answer: bronze

Question: Around what time where alloys starting to get made by humans?
Answer: 1900s
Title: Alloy

The term alloy is used to describe a mixture of atoms in which the primary constituent is a metal. The primary metal is called the base, the matrix, or the solvent. The secondary constituents are often called solutes. If there is a mixture of only two types of atoms, not counting impurities, such as a copper-nickel alloy, then it is called a binary alloy. If there are three types of atoms forming the mixture, such as iron, nickel and chromium, then it is called a ternary alloy. An alloy with four constituents is a quaternary alloy, while a five-part alloy is termed a quinary alloy. Because the percentage of each constituent can be varied, with any mixture the entire range of possible variations is called a system. In this respect, all of the various forms of an alloy containing only two constituents, like iron and carbon, is called a binary system, while all of the alloy combinations possible with a ternary alloy, such as alloys of iron, carbon and chromium, is called a ternary system.

Question: The matrix and the solvent are other names for what?
Answer: The primary metal

Question: What is another name for solutes?
Answer: The secondary constituents

Question: What is the name of an alloy that has  four constituents?
Answer: quaternary alloy

Question: A five-part alloy is known as?
Answer: ternary alloy
Title: Alloy

Although an alloy is technically an impure metal, when referring to alloys, the term "impurities" usually denotes those elements which are not desired. These impurities are often found in the base metals or the solutes, but they may also be introduced during the alloying process. For instance, sulfur is a common impurity in steel. Sulfur combines readily with iron to form iron sulfide, which is very brittle, creating weak spots in the steel. Lithium, sodium and calcium are common impurities in aluminium alloys, which can have adverse effects on the structural integrity of castings. Conversely, otherwise pure-metals that simply contain unwanted impurities are often called "impure metals" and are not usually referred to as alloys. Oxygen, present in the air, readily combines with most metals to form metal oxides; especially at higher temperatures encountered during alloying. Great care is often taken during the alloying process to remove excess impurities, using fluxes, chemical additives, or other methods of extractive metallurgy.

Question: What is a characteristic of iron sulfide?
Answer: very brittle

Question: What makes pure metals impure metals?
Answer: unwanted impurities

Question: Using fluxes and chemical additives during the alloying process does what?
Answer: remove excess impurities

Question: What are the three common impurities in aluminum alloys?
Answer: Lithium, sodium and calcium
Title: Alloy

The term "alloy" is sometimes used in everyday speech as a synonym for a particular alloy. For example, automobile wheels made of an aluminium alloy are commonly referred to as simply "alloy wheels", although in point of fact steels and most other metals in practical use are also alloys. Steel is such a common alloy that many items made from it, like wheels, barrels, or girders, are simply referred to by the name of the item, assuming it is made of steel. When made from other materials, they are typically specified as such, (i.e.: "bronze wheel," "plastic barrel," or "wood girder").

Question: What is the name of a common alloy?
Answer: Steel

Question: What is something on a car that sometimes is made of alloy?
Answer: automobile wheels

Question: Steel and other very practical metals are also named what?
Answer: alloys
Title: Alloy

Alloying a metal is done by combining it with one or more other metals or non-metals that often enhance its properties. For example, steel is stronger than iron, its primary element. The electrical and thermal conductivity of alloys is usually lower than that of the pure metals. The physical properties, such as density, reactivity, Young's modulus of an alloy may not differ greatly from those of its elements, but engineering properties such as tensile strength and shear strength may be substantially different from those of the constituent materials. This is sometimes a result of the sizes of the atoms in the alloy, because larger atoms exert a compressive force on neighboring atoms, and smaller atoms exert a tensile force on their neighbors, helping the alloy resist deformation. Sometimes alloys may exhibit marked differences in behavior even when small amounts of one element are present. For example, impurities in semiconducting ferromagnetic alloys lead to different properties, as first predicted by White, Hogan, Suhl, Tian Abrie and Nakamura. Some alloys are made by melting and mixing two or more metals. Bronze, an alloy of copper and tin, was the first alloy discovered, during the prehistoric period now known as the bronze age; it was harder than pure copper and originally used to make tools and weapons, but was later superseded by metals and alloys with better properties. In later times bronze has been used for ornaments, bells, statues, and bearings. Brass is an alloy made from copper and zinc.

Question: What can be done to a metal to enhance its properties?
Answer: combining it with one or more other metals or non-metals

Question: Pure metals have a higher electrical and thermal conductivity than what?
Answer: alloys

Question: When copper and tin is mixed, what is made?
Answer: Bronze

Question: When was the bronze age?
Answer: prehistoric period

Question: Copper and zinc combine to make what?
Answer: Brass
Title: Alloy

Alloys are often made to alter the mechanical properties of the base metal, to induce hardness, toughness, ductility, or other desired properties. Most metals and alloys can be work hardened by creating defects in their crystal structure. These defects are created during plastic deformation, such as hammering or bending, and are permanent unless the metal is recrystallized. However, some alloys can also have their properties altered by heat treatment. Nearly all metals can be softened by annealing, which recrystallizes the alloy and repairs the defects, but not as many can be hardened by controlled heating and cooling. Many alloys of aluminium, copper, magnesium, titanium, and nickel can be strengthened to some degree by some method of heat treatment, but few respond to this to the same degree that steel does.

Question: What kind of treatment can be made to alter it's properties?
Answer: heat treatment

Question: Softening metals can be achieved by?
Answer: annealing

Question: Aluminium, copper, magnesium, titanium, and nickel can be strengthened by?
Answer: heat treatment

Question: Annealling softens metals by achieving what?
Answer: recrystallizes the alloy and repairs the defects
Title: Alloy

At a certain temperature, (usually between 1,500 °F (820 °C) and 1,600 °F (870 °C), depending on carbon content), the base metal of steel undergoes a change in the arrangement of the atoms in its crystal matrix, called allotropy. This allows the small carbon atoms to enter the interstices of the iron crystal, diffusing into the iron matrix. When this happens, the carbon atoms are said to be in solution, or mixed with the iron, forming a single, homogeneous, crystalline phase called austenite. If the steel is cooled slowly, the iron will gradually change into its low temperature allotrope. When this happens the carbon atoms will no longer be soluble with the iron, and will be forced to precipitate out of solution, nucleating into the spaces between the crystals. The steel then becomes heterogeneous, being formed of two phases; the carbon (carbide) phase cementite, and ferrite. This type of heat treatment produces steel that is rather soft and bendable. However, if the steel is cooled quickly the carbon atoms will not have time to precipitate. When rapidly cooled, a diffusionless (martensite) transformation occurs, in which the carbon atoms become trapped in solution. This causes the iron crystals to deform intrinsically when the crystal structure tries to change to its low temperature state, making it very hard and brittle.

Question: What is the name of steel when it is being formed of two phases?
Answer: heterogeneous

Question: What are the two phases when steel becomes heterogenous?
Answer: carbon (carbide) phase cementite, and ferrite

Question: What are the characteristics of steel if it is cooled to quickly?
Answer: very hard and brittle

Question: Soft and bendable steel is caused by what?
Answer: If the steel is cooled slowly

Question: Allotrophy happens between what temperatures?
Answer: 1,500 °F (820 °C) and 1,600 °F (870 °C)
Title: Alloy

Conversely, most heat-treatable alloys are precipitation hardening alloys, which produce the opposite effects that steel does. When heated to form a solution and then cooled quickly, these alloys become much softer than normal, during the diffusionless transformation, and then harden as they age. The solutes in these alloys will precipitate over time, forming intermetallic phases, which are difficult to discern from the base metal. Unlike steel, in which the solid solution separates to form different crystal phases, precipitation hardening alloys separate to form different phases within the same crystal. These intermetallic alloys appear homogeneous in crystal structure, but tend to behave heterogeneous, becoming hard and somewhat brittle.

Question: Precipitation hardening alloys produce the opposite effects of?
Answer: steel

Question: Precipitation hardening alloys are sometimes also?
Answer: heat-treatable alloys

Question: What makes alloys more softer than normal?
Answer: When heated to form a solution and then cooled quickly
Title: Alloy

When a molten metal is mixed with another substance, there are two mechanisms that can cause an alloy to form, called atom exchange and the interstitial mechanism. The relative size of each element in the mix plays a primary role in determining which mechanism will occur. When the atoms are relatively similar in size, the atom exchange method usually happens, where some of the atoms composing the metallic crystals are substituted with atoms of the other constituent. This is called a substitutional alloy. Examples of substitutional alloys include bronze and brass, in which some of the copper atoms are substituted with either tin or zinc atoms. With the interstitial mechanism, one atom is usually much smaller than the other, so cannot successfully replace an atom in the crystals of the base metal. The smaller atoms become trapped in the spaces between the atoms in the crystal matrix, called the interstices. This is referred to as an interstitial alloy. Steel is an example of an interstitial alloy, because the very small carbon atoms fit into interstices of the iron matrix. Stainless steel is an example of a combination of interstitial and substitutional alloys, because the carbon atoms fit into the interstices, but some of the iron atoms are replaced with nickel and chromium atoms.

Question: Bronze and brass are examples of what?
Answer: substitutional alloys

Question: Tin or zinc atoms in place of copper atoms create?
Answer: substitutional alloys

Question: What is the name of one interstitial alloy?
Answer: Steel

Question: Stainless steel is an example of what two alloys?
Answer: interstitial and substitutional
Title: Alloy

The use of alloys by humans started with the use of meteoric iron, a naturally occurring alloy of nickel and iron. It is the main constituent of iron meteorites which occasionally fall down on Earth from outer space. As no metallurgic processes were used to separate iron from nickel, the alloy was used as it was. Meteoric iron could be forged from a red heat to make objects such as tools, weapons, and nails. In many cultures it was shaped by cold hammering into knives and arrowheads. They were often used as anvils. Meteoric iron was very rare and valuable, and difficult for ancient people to work.

Question: What was one of the first alloys used by humans?
Answer: meteoric iron

Question: What is meteoric iron composed of?
Answer: nickel and iron

Question: What can forged meteoric iron make?
Answer: tools, weapons, and nails

Question: Where does meteoric iron come from?
Answer: iron meteorites

Question: How does meteoric iron come to earth?
Answer: occasionally fall down on Earth from outer space
Title: Alloy

Iron is usually found as iron ore on Earth, except for one deposit of native iron in Greenland, which was used by the Inuit people. Native copper, however, was found worldwide, along with silver, gold and platinum, which were also used to make tools, jewelry, and other objects since Neolithic times. Copper was the hardest of these metals, and the most widely distributed. It became one of the most important metals to the ancients. Eventually, humans learned to smelt metals such as copper and tin from ore, and, around 2500 BC, began alloying the two metals to form bronze, which is much harder than its ingredients. Tin was rare, however, being found mostly in Great Britain. In the Middle East, people began alloying copper with zinc to form brass. Ancient civilizations took into account the mixture and the various properties it produced, such as hardness, toughness and melting point, under various conditions of temperature and work hardening, developing much of the information contained in modern alloy phase diagrams. Arrowheads from the Chinese Qin dynasty (around 200 BC) were often constructed with a hard bronze-head, but a softer bronze-tang, combining the alloys to prevent both dulling and breaking during use.

Question: Where is the only iron deposit on earth?
Answer: Greenland

Question: Around what time did bronze start being formed?
Answer: 2500 BC

Question: What does copper and zinc form to make?
Answer: brass

Question: Where is tin mostly found?
Answer: Great Britain

Question: Which metal important to the ancients is the hardest one?
Answer: Copper
Title: Alloy

Mercury has been smelted from cinnabar for thousands of years. Mercury dissolves many metals, such as gold, silver, and tin, to form amalgams (an alloy in a soft paste, or liquid form at ambient temperature). Amalgams have been used since 200 BC in China for plating objects with precious metals, called gilding, such as armor and mirrors. The ancient Romans often used mercury-tin amalgams for gilding their armor. The amalgam was applied as a paste and then heated until the mercury vaporized, leaving the gold, silver, or tin behind. Mercury was often used in mining, to extract precious metals like gold and silver from their ores.

Question: What does mercury make most metals do?
Answer: dissolves

Question: Since when have Amalgams been used?
Answer: 200 BC

Question: What did ancient Romans use to gild their armor?
Answer: mercury-tin amalgams

Question: Gold and silver were extracted from their ores by using?
Answer: Mercury
Title: Alloy

Many ancient civilizations alloyed metals for purely aesthetic purposes. In ancient Egypt and Mycenae, gold was often alloyed with copper to produce red-gold, or iron to produce a bright burgundy-gold. Gold was often found alloyed with silver or other metals to produce various types of colored gold. These metals were also used to strengthen each other, for more practical purposes. Copper was often added to silver to make sterling silver, increasing its strength for use in dishes, silverware, and other practical items. Quite often, precious metals were alloyed with less valuable substances as a means to deceive buyers. Around 250 BC, Archimedes was commissioned by the king to find a way to check the purity of the gold in a crown, leading to the famous bath-house shouting of "Eureka!" upon the discovery of Archimedes' principle.

Question: Ancient civilizations often alloyed metals for what reason?
Answer: purely aesthetic purposes

Question: Red gold is made by combining gold with?
Answer: copper

Question:  Around what time was the Archimedes' principle discovered?
Answer: 250 BC

Question: Who shouted "Eureka!" while checking the purity of a crown?
Answer: Archimedes

Question: Buyers were often deceived when precious metals were mixed with?
Answer: less valuable substances
Title: Alloy

The term pewter covers a variety of alloys consisting primarily of tin. As a pure metal, tin was much too soft to be used for any practical purpose. However, in the Bronze age, tin was a rare metal and, in many parts of Europe and the Mediterranean, was often valued higher than gold. To make jewelry, forks and spoons, or other objects from tin, it was usually alloyed with other metals to increase its strength and hardness. These metals were typically lead, antimony, bismuth or copper. These solutes sometimes were added individually in varying amounts, or added together, making a wide variety of things, ranging from practical items, like dishes, surgical tools, candlesticks or funnels, to decorative items such as ear rings and hair clips.

Question: Pewter is mostly made up of?
Answer: tin

Question: Why was tin was rarely used for everyday use?
Answer: too soft

Question: During the bronze age, which metal was valued higher than gold in Europe and the Mediterranean?
Answer: tin

Question: What was done to tin to make it stronger?
Answer: alloyed with other metals

Question: What metals were alloyed with tin to make it stronger?
Answer: lead, antimony, bismuth or copper
Title: Alloy

The first known smelting of iron began in Anatolia, around 1800 BC. Called the bloomery process, it produced very soft but ductile wrought iron. By 800 BC, iron-making technology had spread to Europe, arriving in Japan around 700 AD. Pig iron, a very hard but brittle alloy of iron and carbon, was being produced in China as early as 1200 BC, but did not arrive in Europe until the Middle Ages. Pig iron has a lower melting point than iron, and was used for making cast-iron. However, these metals found little practical use until the introduction of crucible steel around 300 BC. These steels were of poor quality, and the introduction of pattern welding, around the 1st century AD, sought to balance the extreme properties of the alloys by laminating them, to create a tougher metal. Around 700 AD, the Japanese began folding bloomery-steel and cast-iron in alternating layers to increase the strength of their swords, using clay fluxes to remove slag and impurities. This method of Japanese swordsmithing produced one of the purest steel-alloys of the early Middle Ages.

Question: Where did smelting of iron begin?
Answer: Anatolia

Question: When did the smelting of iron first begin?
Answer: around 1800 BC

Question: When did iron making technology begin in Japan?
Answer: around 700 AD

Question: Pig iron is composed of iron and what else?
Answer: carbon

Question: What makes Pig iron different from regular iron?
Answer: lower melting point