US20160201170A1

US20160201170A1 - Molten aluminum resistant alloys

Info

Publication number: US20160201170A1
Application number: US14/991,154
Authority: US
Inventors: Kenneth Vecchio; James Vecchio; Justin Lee Cheney
Original assignee: Scoperta Inc
Current assignee: Scoperta Inc
Priority date: 2015-01-09
Filing date: 2016-01-08
Publication date: 2016-07-14
Also published as: WO2016112341A1

Abstract

Embodiments of methods for protection a material from a reaction from molten aluminum. In some embodiments, a coating can be applied over a substrate which has significantly less of a reaction rate with molten aluminum, thus preventing damage or chemical changes to the substrate. The coating alloy can be formed from cast iron in combination with niobium in some embodiments.

Description

INCORPORATION BY REFERENCE TO ANY PRIORITY APPLICATIONS

Any and all applications for which a foreign or domestic priority claim is identified in the Application Data Sheet as filed with the present application are hereby incorporated by reference under 37 CFR 1.57.

BACKGROUND

1. Field
This disclosure generally relates to materials and coatings which can be resistant to flowing molten aluminum, and methods for producing the same.
2. Description of the Related Art
Casting components can degrade due to their reaction with molten aluminum during the manufacturing of aluminum parts within the casting component. The reaction rate between the casting component and the molten aluminum thus can govern the lifetime of the components' utility. The reaction rate can be increased and lifetime decreased when the component is subject to contact with flowing aluminum due to the component experiencing more of a reaction with the molten aluminum.
One conventional material used to create components by the aluminum casting industry due to its relatively high resistance to molten aluminum is H13 steel. H13 steel has the composition of: Fe-bal, C: 0.32-0.40, Cr: 5.13-5.25, Mo: 1.33-1.4, Si: 1, V: 1, and the steel is air or oil quenched from 1000° C.-1025° C.

SUMMARY

Disclosed herein in some embodiments are methods of protecting a component from molten aluminum reaction. The method may comprise coating a component formed from a base material with an alloy, wherein the alloy has a reaction rate to aluminum less than 50% than that of the base material.
In some embodiments, the alloy can be a Nb—Zr alloy with 30-60 wt. % Zr. In some embodiments, the alloy can be a grey cast iron. In some embodiments, the alloy can be a pseudo alloy of grey cast iron and niobium according to the formula: (grey cast iron)_100-xNb_xwith x ranging from 10 to 30 wt. %. In some embodiments, the alloy can be a pseudo alloy of grey cast iron and niobium according to the formula: (grey cast iron)_100-xNb_xwith x ranging from 0 to 10 wt. %.
In some embodiments, the alloy can have a reaction rate less than 10% than that of the base material. In some embodiments, the alloy can have a reaction rate less than 5% than that of the base material.
Also disclosed herein are embodiments of an alloy resistant to molten aluminum, the alloy comprising two or more elements, wherein the alloy has a reaction level of less than 38 atom %, wherein the reaction level is calculated by determining a minimum alloy content in a pseudo binary alloy/aluminum phase diagram where the liquidus temperature is at or above 1500K. In some embodiments, the reaction level can be 10 atom % or less. In some embodiments, the reaction level can be 5 atom % or less.
In some embodiments, the alloy can be a Nb—Zr alloy with 30-60 wt. % Zr. In some embodiments, the alloy can be a grey cast iron. In some embodiments, the alloy can be a pseudo alloy of grey cast iron and niobium according to the formula: (grey cast iron)_100-xNb_xwith x ranging from 10 to 30 wt. %. In some embodiments, the alloy can be a pseudo alloy of grey cast iron and niobium according to the formula: (grey cast iron)_100-xNb_xwith x ranging from 0 to 10 wt. %.
Also disclosed herein are embodiments of an alloy resistant to molten aluminum, the alloy comprising two or more elements, wherein the alloy has a reaction level of less than 40 atom %, wherein the reaction level is calculated by determining a minimum alloy content in a pseudo binary alloy/aluminum phase diagram where the liquidus temperature is at or above 1500K. In some embodiments, the reaction level can be 10 atom % or less. In some embodiments, the reaction level can be 5 atom % or less.
Also disclosed herein are embodiments of an article of manufacture for use in an aluminum casting process, the article comprising at least a portion of an alloy, wherein the alloy has a reaction rate in molten aluminum of less than or equal to ½ the rate of H13 steel.
In some embodiments, the alloy can be a grey cast iron. In some embodiments, the alloy can be pseudo alloy of grey cast iron and niobium according to the formula: (grey cast iron)_100-xNb_xwith x ranging from 0 to 10 wt. %.
In some embodiments, the alloy can have a reaction rate less than 10% than that of the base material. In some embodiments, the alloy can have a reaction rate less than 5% than that of the base material.
Also disclosed herein are embodiments of a casting component for casting aluminum, wherein the casting component is either clad with or is comprised of a metal alloy composition, the metal alloy composition having a reaction level of about 38 atom % or less, wherein the reaction level is defined as the minimum alloy content of the metal alloy composition in the phase diagram between aluminum and the metal alloy composition where the liquidus curve is at or above 1500 K.
In some embodiments, the alloy can have a reaction rate in molten aluminum of less than or equal to ½ the rate of H13 steel. In some embodiments, a % loss of an alloy rod, based on area loss and diameter loss, formed the metal alloy composition can be less than 5% after undergoing a molten aluminum flow rate of 0.2 meters/second.
Also disclosed herein are embodiments of a casting component for casting aluminum, wherein the casting component is either clad with or is comprised of a metal alloy composition, the metal alloy composition having a reaction level of about 40 atom % or less, wherein the reaction level is defined as the minimum alloy content of the metal alloy composition in the phase diagram between aluminum and the metal alloy composition where the liquidus curve is at or above 1500 K.
Also disclosed herein are embodiments of a method of casting aluminum, comprising providing molten aluminum into contact with a surface of a casting component, wherein the casting component is either clad with or is comprised of a metal alloy composition, the metal alloy composition having a reaction level of about 38 atom % or less, wherein the reaction level is defined as the minimum alloy content of the metal alloy composition in the phase diagram between aluminum and the metal alloy composition where the liquidus curve is at or above 1500 K; and casting the molten aluminum.
Also disclosed herein are embodiments of a method of casting aluminum, comprising providing molten aluminum into contact with a surface of a casting component, wherein the casting component is either clad with or is comprised of a metal alloy composition, the metal alloy composition having a reaction level of about 40 atom % or less, wherein the reaction level is defined as the minimum alloy content of the metal alloy composition in the phase diagram between aluminum and the metal alloy composition where the liquidus curve is at or above 1500 K; and casting the molten aluminum.
Also disclosed herein are embodiments of a method of protecting a component from molten aluminum reaction, the method comprising coating a component formed from a base material with an alloy, wherein the alloy has a reaction level to molten aluminum of less than 38 atomic %, the reaction level being calculated by determining a minimum alloy content in a pseudo binary alloy/aluminum phase diagram where the liquidus temperature is at or above 1500K, and wherein the alloy has a minimum concentration of highly resistant secondary phases of 5 mole %.
Also disclosed herein are embodiments of a method of protecting a component from molten aluminum reaction, the method comprising coating a component formed from a base material with an alloy, wherein the alloy has a reaction level to molten aluminum of less than 40 atomic %, the reaction level being calculated by determining a minimum alloy content in a pseudo binary alloy/aluminum phase diagram where the liquidus temperature is at or above 1500K, and wherein the alloy has a minimum concentration of highly resistant secondary phases of 5 mole %.
In some embodiments, the alloy can be a Nb—Zr alloy with 30-60 wt. % Zr. In some embodiments, the alloy can have a reaction rate to molten aluminum less than 50% than that of the base material. In some embodiments, the alloy can be a pseudo alloy of grey cast iron and niobium according to the formula: (grey cast iron)_100-xNb_xwith x ranging from 10 to 30 wt. %. In some embodiments, the alloy can be a pseudo alloy of grey cast iron and niobium according to the formula: (grey cast iron)_100-xNb_xwith x ranging from 0 to 10 wt. %. In some embodiments, the alloy can have a reaction rate less than 10% than that of the base material. In some embodiments, the alloy can have a reaction rate less than 5% than that of the base material.
Also disclosed herein are embodiments of an alloy resistant to molten aluminum, the alloy comprising two or more elements, a reaction level of less than 38 atom %, wherein the reaction level is calculated by determining a minimum alloy content in a pseudo binary alloy/aluminum phase diagram where the liquidus temperature is at or above 1500K, and a minimum concentration of highly resistant secondary phases of 5 mole %.
In some embodiments, the reaction level can be 10 atom % or less. In some embodiments, the reaction level can be 5 atom % or less. In some embodiments, the alloy can be a Nb—Zr alloy with 30-60 wt. % Zr.
Also disclosed herein are embodiments of an alloy resistant to molten aluminum, the alloy comprising two or more elements, a reaction level of less than 40 atom %, wherein the reaction level is calculated by determining a minimum alloy content in a pseudo binary alloy/aluminum phase diagram where the liquidus temperature is at or above 1500K, and a minimum concentration of highly resistant secondary phases of 5 mole %.
In some embodiments, the alloy can be a pseudo alloy of grey cast iron and niobium according to the formula: (grey cast iron)_100-xNb_xwith x ranging from 10 to 30 wt. %. In some embodiments, the alloy can be a pseudo alloy of grey cast iron and niobium according to the formula: (grey cast iron)_100-xNb_xwith x ranging from 0 to 10 wt. %. In some embodiments, the alloy can have a minimum concentration of highly resistant secondary phases of 10 mole %. In some embodiments, the alloy can have a minimum concentration of highly resistant secondary phases of 20 mole %.
In some embodiments, the alloy can comprise Fe and the following in weight percent: Nb: about 10, Si: 0 to about 2, Mn: 0 to about 2, and C: 0 to about 2.5. In some embodiments, the alloy can comprise Fe and one of the following in weight percent: Nb: about 10, Si: about 1.6, Mn: about 0.5, C: about 2.5; Nb: about 10, Si: about 1.6, Mn: about 0.5, C: about 2.0; Nb: about 10, Si: about 1.6, Mn: about 0.5, C: about 1.5; or Nb: about 10, Si: about 1.6, Mn: about 0.5, C: about 1.0.
In some embodiments, the alloy can be a coating on a base substrate. In some embodiments, the alloy can be a casting component for casting molten aluminum.
Also disclosed herein are embodiments of an article of manufacture for use in an aluminum casting process, the article comprising an alloy forming at least a portion of the article, wherein the alloy has a reaction level to molten aluminum of less than 38 atomic %, the reaction level being calculated by determining a minimum alloy content in a pseudo binary alloy/aluminum phase diagram where the liquidus temperature is at or above 1500K, and wherein the alloy has a minimum concentration of highly resistant secondary phases of 5 mole %.
In some embodiments, the alloy can be a grey cast iron. In some embodiments, the alloy can have a reaction rate in molten aluminum of less than or equal to ½ the rate of H13 steel. In some embodiments, the alloy can be pseudo alloy of grey cast iron and niobium according to the formula: (grey cast iron)_100-xNb_xwith x ranging from 0 to 10 wt. %. In some embodiments, the alloy can have a reaction rate less than 10% than that of the H13 steel. In some embodiments, the alloy can have a reaction rate less than 5% than that of the H13 steel.
Also disclosed herein are embodiments of an article of manufacture for use in an aluminum casting process, the article comprising an alloy forming at least a portion of the article, wherein the alloy has a reaction level to molten aluminum of less than 40 atomic %, the reaction level being calculated by determining a minimum alloy content in a pseudo binary alloy/aluminum phase diagram where the liquidus temperature is at or above 1500K, and wherein the alloy has a minimum concentration of highly resistant secondary phases of 5 mole %.
Also disclosed herein are embodiments of a method of protecting a component from molten aluminum reaction, the method comprising coating a component formed from a base material with an alloy, wherein the alloy has a reaction level to molten aluminum of less than 38 atomic %, the reaction level being calculated by determining a minimum alloy content in a pseudo binary alloy/aluminum phase diagram where the liquidus temperature is at or above 1500K, and wherein the alloy has a minimum concentration of highly resistant secondary phases of 5 mole %.
Also disclosed herein are embodiments of a method of protecting a component from molten aluminum reaction, the method comprising coating a component formed from a base material with an alloy, wherein the alloy has a reaction level to molten aluminum of less than 40 atomic %, the reaction level being calculated by determining a minimum alloy content in a pseudo binary alloy/aluminum phase diagram where the liquidus temperature is at or above 1500K, and wherein the alloy has a minimum concentration of highly resistant secondary phases of 5 mole %.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a phase diagram of an alloy showing calculation of reaction level according to certain embodiments of the disclosure.

FIG. 2 illustrates an SEM micrograph showing reaction width measurement according to certain embodiments of the disclosure.

FIG. 3 illustrates a sample coupon after an aluminum bath exposure showing area loss measurements according to certain embodiments of the disclosure.

DETAILED DESCRIPTION

Disclosed herein are embodiments of several methods for improving the lifetime of casting components that can come into contact (either intentionally or unintentionally) with molten aluminum, as well as alloys and articles resistant to deleterious effects of molten aluminum. Several non-limiting examples of casting components that can have the resistance to molten aluminum include casting nozzles and casting molds, though other casting components could be used as well. In some embodiments, the casting components can be coated with an aluminum-resistant alloy, and thus have a different material substrate underneath the coating, or can be manufactured partially or completely from an aluminum-resistant alloy.
In some embodiments of the present disclosure, a method of protection is described which can involve the cladding, or coating, of conventional components with a material which can have enhanced resistance to molten aluminum. Cladding can involve the deposition of a layer of a high resistance material, and can be deposited using a variety of techniques including, but not limited to: TIG welding, MIG welding, thermal spray, PTA welding, laser cladding, etc. A successful cladding can protect the component from contact with the molten aluminum, and thus the lifetime of the component can be governed by the reaction rate of the cladding material and not the underlying component. In some embodiments, the cladding can increase the lifetime of the component by 10% (or about 10%) or more as compared to the underlying component. In some embodiments, the cladding can increase the lifetime of the component by 200% (or about 200%) or more as compared to the underlying component. In some embodiments, the cladding can increase the lifetime of the component by 400% (or about 400%) or more as compared to the underlying component.
In some embodiments, a method for increasing lifetime is described by which the component itself can be made from an alloy which is highly resistant to molten aluminum. To describe this embodiment, the resistant alloy that is made to use the component itself is compared against a conventional material used to create components by the aluminum casting industry, H13 steel. H13 steel is Fe-bal, C: 0.32-0.40, Cr: 5.13-5.25, Mo: 1.33-1.4, Si: 1, V: 1 which is air or oil quenched from 1000° C.-1025° C.
In some embodiments, the use of a resistant alloy to fabricate the component can increase the lifetime of component by 10% (or about 10%) or more compared to H13 steel. In some embodiments, the use of a resistant alloy to fabricate the component can increase the lifetime by 200% (or about 200%) or more compared to an H13 steel component. In some embodiments, the use of a resistant alloy to fabricate the component can increase the lifetime by 400% (or about 400%) or more compared to a H13 steel component.
As disclosed herein, the term alloy can refer to the chemical composition of powder used to form a desired component, the powder itself (such as feedstock), the composition of a metal component formed, for example, by the heating and/or deposition of the powder, and the metal component itself.

Metal Alloy Composition

In some embodiments, this disclosure can be fully described by the metal alloy compositions. In some embodiments, the alloy compositions can be used to form the cladding layer or used to fabricate the component.
Table 1 lists the alloy chemistries evaluated according to the base element and the alloying element composition (in weight percent). In some embodiments, grey cast iron is listed as the base element. The particular alloys were chosen based on their reaction level with Al determined from a binary phase diagram between the alloying element and Al. In these embodiments, the composition for gray cast iron is the base alloy whereby alloying additions are added. For example, in the case of alloy 25, grey cast iron makes up 90% (or about 90%) of the alloy chemistry and pure Nb makes up the remaining 10% (or about 10%), also commonly written as (grey cast iron)₉₀Nb₁₀. For the purposes of defining alloys in this disclosure grey cast iron is any iron-based material with 2.5 to 4 wt. % carbon (or about 2.5 to about 4 wt. % carbon). In some embodiments, the grey cast iron can contain a graphite phase.

TABLE 1

Experimental Alloys Evaluated in this Study

Alloy	Base Element	Alloying Elements

1	Zr	40% Ta
2	Zr	30% Ta, 10% W
3	Zr	20% Ta, 20% W
4	Zr	10% Ta, 30% W
5	Zr	40% W
6	Ti	40% Ta
7	Ti	30% Ta, 10% W
8	Ti	20% Ta, 20% W
9	Ti	10% Ta, 30% W
10	Ti	40% W
11	Nb	30% Fe
12	Nb	40% Fe
13	Nb	50% Fe
14	Fe	40% Nb
15	Nb	30% Ti
16	Nb	40% Ti
17	Nb	50% Ti
18	Ti	40% Nb
19	Nb	30% Zr
20	Nb	40% Zr
21	Nb	50% Zr
22	Zr	40% Nb
23	Zr	30% Nb
24	Grey Cast Iron	0%
	(GCI)
25	GCI	10% Nb
26	GCI	20% Nb
27	GCI	30% Nb
28	GCI	10% Zr
29	GCI	20% Zr
30	GCI	30% Zr

Other base alloys can be used as well as the above, such as niobium, vanadium, zirconium, titanium, tantalum, tungsten, and molybdenum. In some embodiments, a combination of Nb—V—Zr—Ti may provide advantageous properties. In some embodiments, certain metals can be avoided such as copper, nickel, palladium, hafnium, platinum, iron, chromium, cobalt, and manganese.
In some embodiments, the alloy can be considered a pseudo alloy with a pseudo binary phase diagram. A pseudo binary phase diagram is a common phrase used by metallurgists to describe a phase diagram where one of the sides is not a pure element. In some embodiments such as those shown in the above Table 1, the alloy might be 60Zr-40Nb and a pseudo binary phase diagram can be evaluated where one end of the phase diagram is pure 60Zr-40Nb and the other end is pure Al. This is not a true binary phase diagram because any point on the diagram is really a three element alloy.
In some embodiments, the alloy can be further modified from Alloy 25 presented in Table 1. Specifically, the carbon level can be reduced to reduce or prevent the potential of the weld overlay to crack. In such embodiments, the alloy can comprise the following elemental ranges in weight percent (balance iron):

- Nb: 0 to 10 (or about 0 to about 10)
- Si: 0 to 2 (or about 0 to about 2)
- Mn: 0 to 2 (or about 0 to about 2)
- C: 0 to 2.5 (or about 0 to about 2.5)

In some embodiments, the alloy can comprise the following in weight percent:

- Fe: Bal, Nb: 10, Si: 1.6, Mn: 0.5, C: 2.15 (or Fe: Bal, Nb: about 10, Si: about 1.6, Mn: about 0.5, C: about 2.5)
- Fe: Bal, Nb: 10, Si: 1.6, Mn: 0.5, C: 2.0 (or Fe: Bal, Nb: about 10, Si: about 1.6, Mn: about 0.5, C: about 2.0)
- Fe: Bal, Nb: 10, Si: 1.6, Mn: 0.5, C: 1.5 (or Fe: Bal, Nb: about 10, Si: about 1.6, Mn: about 0.5, C: about 1.5)
- Fe: Bal, Nb: 10, Si: 1.6, Mn: 0.5, C: 1.0 (or Fe: Bal, Nb: about 10, Si: about 1.6, Mn: about 0.5, C: about 1.0)

In some embodiments, for the elements listed above that are listed from 0-X, the alloy may contain a non-zero amount of that element.
The disclosed alloys can incorporate the above elemental constituents to a total of 100 wt. %. In some embodiments, the alloy may include, may be limited to, or may consist essentially of the above named elements. In some embodiments, the alloy may include 2% or less of impurities. Impurities may be understood as elements or compositions that may be included in the alloys due to inclusion in the feedstock components, through introduction in the manufacturing process.
Further, the Fe content identified in all of the compositions described in the above paragraphs may be the balance of the composition as indicated above, or alternatively, the balance (or remainder) of the composition may comprise Fe and other elements. In some embodiments, the balance may consist essentially of Fe and may include incidental impurities.

Thermodynamic Criteria

In some embodiments, this disclosure can be fully described by the thermodynamic criteria, which can be used to predict the desired performance of the alloy. Specifically, certain criteria can be used to define the thermodynamic behavior of the alloys. The criteria can be used to define the reaction rate of the alloy with molten aluminum. The criteria are advantageous in order to use computational metallurgy to design the best performing alloys from the billions of potential choices.
The first criterion is defined as the reaction level [101] shown in FIG. 1. The reaction level is calculated using thermodynamic phase diagrams, such as the Fe—Al phase diagram shown in FIG. 1. The Fe—Al phase diagram shows an example of the methodology for determining the reaction level of an individual element with Al. The reaction level is calculated by evaluating the minimum alloy content of the alloy element that is reacting with Al where the liquidus curve is at or above 1500K, which is a relevant temperature at which an aluminum casting component might operate (e.g., this is the conventional temperature used for casting aluminum parts). As shown in FIG. 1, the reaction level of pure iron according to this criterion would be between 38 atom % (or about 38 atom %) and 40 atom % (or about 40 atom %) as shown at the intersection of the 1500K isotherm with the liquidus line. Decreasing reaction levels can correspond to decreasing reaction rates with molten aluminum and thereby increasing component lifetime. As the reaction level goes down, the reaction rate of the alloy with molten aluminum decreases and component lifetime increases. Therefore, an alloy with a low reaction level can be the most resistant to molten aluminum attack. The reaction level of H13 would be similar to the reaction level of Fe.
If an iron component is in a molten Al environment, the reaction level tells that at 1500K the liquid could have up to 38% dissolved iron in it. A lower reaction level, such as 10%, can indicate that the liquid can contain up to 10% dissolved iron. Therefore, a lower reaction level signifies a decreasing ability of the liquid to dissolve the solid component and thereby an increase in the lifetime of the solid.
In some embodiments, the alloy can have a reaction level of less than 40 atom % (or less than about 40 atom %). In some embodiments, the alloy can have a reaction level of less than 39 atom % (or less than about 39 atom %). In some embodiments, the alloy can have a reaction level of less than 38 atom % (or less than about 38 atom %). In some embodiments, the alloy can have a reaction level of less than 10 atom % (or less than about 10 atom %). In some embodiments, the alloy can have a reaction level of less than 5 atom % (or less than about 5 atom %).
In some embodiments, the alloy can have a reaction level of 40 atom % (or about 40 atom %) or less. In some embodiments, the alloy can have a reaction level of 39 atom % (or about 39 atom %) or less. In some embodiments, the alloy can have a reaction level of 38 atom % (or about 38 atom %) or less. In some embodiments, the alloy can have a reaction level of 10 atom % (or about 10 atom %) or less. In some embodiments, the alloy can have a reaction level of 5 atom % (or about 5 atom %) or less.
The second criterion is the reaction slope at 1500K and is calculated by evaluating the slope of the liquidus curve at 1500K in the alloy/pure aluminum phase diagram. A steeper slope predicts a lower reaction rate and a shallower slope predicts a higher reaction rate. Thus, reaction improvements can be made by increasing the liquidus curve slope at a particular temperature, such as the 1500K discussed in the examples herein.
Accordingly, the general principles discussed herein are to shift the liquidus and temperature isotherm point (at whatever desirable temperature that maybe) towards the Al side of the phase diagram (e.g., making the alloy have more limited solubility of the specific alloy metal with Al) while also increasing the slope of the liquidus curve at that particular temperature (e.g., requiring higher and higher temperatures to achieve more metal solubility in molten Al). This can give alloys which are more resistant to the molten aluminum, thus having less reaction, and may be more easily used in liquid aluminum applications.
It will be understood that 1500K is a representative number that is based on the conventional melting temperature of aluminum. This temperature value can be adjusted as necessary for a particular configuration, for example different aluminum alloys may achieve solidification at higher or lower melting temperatures. The same application as above can be thus applied to those temperatures as well. Further, the phase diagram disclosed with respect to Fe and Al is just one embodiment, and different phase diagrams having different properties can be used as well.
The above two criteria are methods by which the behavior of a homogenous alloy or alloy matrix can be predicted. However, it has been determined in this study through extensive experimentation that the alloy's resistance to molten aluminum can be further enhanced through the growth of secondary phases, which are highly resistant to molten aluminum. Examples of such phases include graphite and/or carbides. Carbides provide the additional advantage of providing some wear resistance to the alloy. In some embodiments, a highly resistant secondary phase can have a measured reaction rate below a certain threshold. In some embodiments, the highly resistant secondary phases can have a measured reaction rate of below 0.5 μm/hr (or below about 0.5 μm/hr).
In some embodiments, the alloy can have a minimum concentration of highly resistant secondary phases. Highly resistant secondary phases are calculated thermodynamically for a given alloy at room temperature and are given in mole fraction. In some embodiments, the alloy can have a minimum of 5 mole % (or about 5 mole %) of highly resistant secondary phases. In some embodiments, the alloy can have a minimum of 10 mole % (or about 10 mole %) of highly resistant secondary phases. In some embodiments, the alloy can have a minimum of 20 mole % (or about 20 mole %) of highly resistant secondary phases.

Performance Criteria

In some embodiments, the alloy can be fully described by a set of performance criteria used to measure the resistance to molten aluminum attack. Through extensive experimentation, two test methods were developed in order to characterize molten aluminum resistivity.
The first method involved submerging the alloy in a molten aluminum bath at 750° C. temperature for 48 hours. In order to draw accurate comparison, H13 steel, a common alloy used in the aluminum casting industry, was tested in this way. The reaction width is used as a metric to characterize the reaction rate of the alloy. As shown in FIG. 2, the reaction width [201] is defined as the distance by which the alloy shows reaction with the molten aluminum. The micrograph shows three distinct regions, 1) unreacted H13 steel [202], 2) a reaction region which of which is used to calculate the reaction width [203], and 3) aluminum rich region [204]. One skilled in the art can easily distinguish all three regions using energy dispersive spectroscopy.
The reaction rate of the material can then be calculated based on the reaction width measurement and the testing time. Reaction rate measurements are shown in Table 2 for a selection of experimental alloys. As shown, the majority of experimental alloys tested do not show an improvement in reaction rate, thus demonstrating the difficulty in designing such an alloy. Also shown is the improvement factor over H13 steel, which is a useful metric to define the molten aluminum resistance of the alloy.
In some embodiments, the alloy can show a molten aluminum resistance which is 2 times or better (or about 2 times or more better) than a base material, such as H13 steel. In some embodiments, the alloy can show a molten aluminum resistance which is 10 times or better (or about 10 times or more better) than H13 steel. In some embodiments, the alloy can show a molten aluminum resistance which is 40 times or better (or about 40 times or more better) than H13 steel.
Accordingly, in some embodiments where the alloy is coated on a base material, the alloy can have a reaction rate to molten aluminum that is less than 50% (or less than about 50%) than the reaction rate of the base material it is coated on, such as H13 steel. In some embodiments, the alloy can have a reaction rate that is less than 10% (or less than about 10%) than the reaction rate of the base material it is coated on. In some embodiments, the alloy can have a reaction rate that is less than 5% (or less than about 5%) than the reaction rate of the base material it is coated on.

TABLE 2

Reaction Rates of Experimental Alloys

#	Sample	um/hr	Improvement Factor

1	60Zr-40Nb	0.22	40.9
2	50Zr-50Nb	0.25	36.0
3	40Zr-60Nb	0.27	33.3
4	Grey Cast Fe	0.5	18.0
5	30Zr-70Nb	2.2	4.1
6	60Fe-40Nb	4.2	2.1
7	H13 #3	9	1.0
8	H13 #2	9.3	1.0
9	50Fe-50Nb	11.1	0.8
10	H13 #1	12.2	0.7
11	40Ti-60Nb	12.5	0.7
12	30Ti-70Nb	13.7	0.7
13	40Fe-60Nb	14.2	0.6
14	60Ti-40Nb	32.8	0.3
15	30Fe-70Nb	35.1	0.3
16	50Ti-50Nb	48.9	0.2

A second method was devised in order to characterize the resistance of the alloy in the presence of flowing molten aluminum. In this method, a 0.25″ diameter alloy rod was manufactured and spun in a bath of molten aluminum at a 470 rotational speed. These testing conditions resulted in a flow rate of 0.2 meters/second on the surface of the alloy coupon. The performance of the experimental alloys in this test is shown in Table 3. The diameter and area loss of the specimen is measured according to FIG. 3. The original diameter of the sample [302] and the diameter of the un-reacted area of the sample after exposure [301] are used to calculate the % loss of each experimental alloy composition. It can be advantageous to have a % loss less than that of H13.

TABLE 3

Reaction Rates of alloys in 2^ndmethod.

	Sample	Area Loss	Dia. Loss	% Loss

	H13 #
2	2.61	0.14	5.94
	70Zr-30Nb	0.65	0.048	1.47
	60Zr-40Nb	0.66	0.06	1.49
	50Zr-50Nb	0.11	0.029	0.25
	40Zr-60Nb	4.22	0.24	8.64
	GCI-10Zr	8.67	0.58	19.5
	GCI-20Zr	4.11	0.34	9.4
	GCI-30Zr	21.49	1.57	45.79
	GCI-10Nb	1.51	0.11	3.36
	GCI-20Nb	7.44	0.86	16.9
	GCI-30Nb	4.1	0.057	9.4

From the foregoing description, it will be appreciated that an inventive alloys resistant to molten aluminum are disclosed. While several components, techniques and aspects have been described with a certain degree of particularity, it is manifest that many changes can be made in the specific designs, constructions and methodology herein above described without departing from the spirit and scope of this disclosure.
Certain features that are described in this disclosure in the context of separate implementations can also be implemented in combination in a single implementation. Conversely, various features that are described in the context of a single implementation can also be implemented in multiple implementations separately or in any suitable subcombination. Moreover, although features may be described above as acting in certain combinations, one or more features from a claimed combination can, in some cases, be excised from the combination, and the combination may be claimed as any subcombination or variation of any subcombination.
Moreover, while methods may be depicted in the drawings or described in the specification in a particular order, such methods need not be performed in the particular order shown or in sequential order, and that all methods need not be performed, to achieve desirable results. Other methods that are not depicted or described can be incorporated in the example methods and processes. For example, one or more additional methods can be performed before, after, simultaneously, or between any of the described methods. Further, the methods may be rearranged or reordered in other implementations. Also, the separation of various system components in the implementations described above should not be understood as requiring such separation in all implementations, and it should be understood that the described components and systems can generally be integrated together in a single product or packaged into multiple products. Additionally, other implementations are within the scope of this disclosure.
Conditional language, such as “can,” “could,” “might,” or “may,” unless specifically stated otherwise, or otherwise understood within the context as used, is generally intended to convey that certain embodiments include or do not include, certain features, elements, and/or steps. Thus, such conditional language is not generally intended to imply that features, elements, and/or steps are in any way required for one or more embodiments.
Conjunctive language such as the phrase “at least one of X, Y, and Z,” unless specifically stated otherwise, is otherwise understood with the context as used in general to convey that an item, term, etc. may be either X, Y, or Z. Thus, such conjunctive language is not generally intended to imply that certain embodiments require the presence of at least one of X, at least one of Y, and at least one of Z.
Language of degree used herein, such as the terms “approximately,” “about,” “generally,” and “substantially” as used herein represent a value, amount, or characteristic close to the stated value, amount, or characteristic that still performs a desired function or achieves a desired result. For example, the terms “approximately”, “about”, “generally,” and “substantially” may refer to an amount that is within less than or equal to 10% of, within less than or equal to 5% of, within less than or equal to 1% of, within less than or equal to 0.1% of, and within less than or equal to 0.01% of the stated amount. If the stated amount is 0 (e.g., none, having no), the above recited ranges can be specific ranges, and not within a particular % of the value. For example, within less than or equal to 10 wt./vol. % of, within less than or equal to 5 wt./vol. % of, within less than or equal to 1 wt./vol. % of, within less than or equal to 0.1 wt./vol. % of, and within less than or equal to 0.01 wt./vol. % of the stated amount.
Some embodiments have been described in connection with the accompanying drawings. The figures are drawn to scale, but such scale should not be limiting, since dimensions and proportions other than what are shown are contemplated and are within the scope of the disclosed inventions. Distances, angles, etc. are merely illustrative and do not necessarily bear an exact relationship to actual dimensions and layout of the devices illustrated. Components can be added, removed, and/or rearranged. Further, the disclosure herein of any particular feature, aspect, method, property, characteristic, quality, attribute, element, or the like in connection with various embodiments can be used in all other embodiments set forth herein. Additionally, it will be recognized that any methods described herein may be practiced using any device suitable for performing the recited steps.
While a number of embodiments and variations thereof have been described in detail, other modifications and methods of using the same will be apparent to those of skill in the art. Accordingly, it should be understood that various applications, modifications, materials, and substitutions can be made of equivalents without departing from the unique and inventive disclosure herein or the scope of the claims.

Claims

What is claimed is:

1. A method of protecting a component from molten aluminum reaction, the method comprising:

coating a component formed from a base material with an alloy;

wherein the alloy has a reaction level to molten aluminum of less than 38 atomic %, the reaction level being calculated by determining a minimum alloy content in a pseudo binary alloy/aluminum phase diagram where the liquidus temperature is at or above 1500K; and

wherein the alloy has a minimum concentration of highly resistant secondary phases of 5 mole %.

2. The method of claim 1, wherein the alloy is a Nb—Zr alloy with 30-60 wt. % Zr.

3. The method of claim 1, wherein the alloy has a reaction rate to molten aluminum less than 50% than that of the base material.

4. The method of claim 1, wherein the alloy is a pseudo alloy of grey cast iron and niobium according to the formula: (grey cast iron)_100-xNb_xwith x ranging from 10 to 30 wt. %.

5. The method of claim 1, wherein the alloy is a pseudo alloy of grey cast iron and niobium according to the formula: (grey cast iron)_100-xNb_xwith x ranging from 0 to 10 wt. %.

6. The method of claim 1, wherein the alloy has a reaction rate less than 10% than that of the base material.

7. The method of claim 1, wherein the alloy has a reaction rate less than 5% than that of the base material.

8. An alloy resistant to molten aluminum, the alloy comprising:

two or more elements;

a reaction level of less than 38 atom %, wherein the reaction level is calculated by determining a minimum alloy content in a pseudo binary alloy/aluminum phase diagram where the liquidus temperature is at or above 1500K; and

a minimum concentration of highly resistant secondary phases of 5 mole %.

9. The alloy of claim 8, wherein the reaction level is 10 atom % or less.

10. The alloy of claim 8, wherein the reaction level is 5 atom % or less.

11. The alloy of claim 8, wherein the alloy is a Nb—Zr alloy with 30-60 wt. % Zr.

12. The alloy of claim 8, wherein the alloy is a pseudo alloy of grey cast iron and niobium according to the formula: (grey cast iron)_100-xNb_xwith x ranging from 10 to 30 wt. %.

13. The alloy of claim 8, wherein the alloy is a pseudo alloy of grey cast iron and niobium according to the formula: (grey cast _iron)_100-xNb_xwith x ranging from 0 to 10 wt. %.

14. The alloy of claim 8, wherein the alloy has a minimum concentration of highly resistant secondary phases of 10 mole %.

15. The alloy of claim 8, wherein the alloy has a minimum concentration of highly resistant secondary phases of 20 mole %.

16. The alloy of claim 8, wherein the alloy comprises Fe and the following in weight percent:

Nb: about 10;

Si: 0 to about 2;

Mn: 0 to about 2; and

C: 0 to about 2.5.

17. The alloy of claim 8, wherein the alloy comprises Fe and one of the following in weight percent:

Nb: about 10, Si: about 1.6, Mn: about 0.5, C: about 2.5;

Nb: about 10, Si: about 1.6, Mn: about 0.5, C: about 2.0;

Nb: about 10, Si: about 1.6, Mn: about 0.5, C: about 1.5; or

Nb: about 10, Si: about 1.6, Mn: about 0.5, C: about 1.0.

18. The alloy of claim 8, wherein the alloy is a coating on a base substrate.

19. The alloy of claim 8, wherein the alloy is a casting component for casting molten aluminum.

20. An article of manufacture for use in an aluminum casting process, the article comprising:

an alloy forming at least a portion of the article;

21. The article of manufacture of claim 20, wherein the alloy is a grey cast iron.

22. The article of manufacture of claim 20, wherein the alloy has a reaction rate in molten aluminum of less than or equal to ½ the rate of H13 steel.

23. The article of manufacture of claim 20, wherein the alloy is pseudo alloy of grey cast iron and niobium according to the formula: (grey cast iron)_100-xNb_xwith x ranging from 0 to 10 wt. %.

24. The article of manufacture of claim 20, wherein the alloy has a reaction rate less than 10% than that of the H13 steel.

25. The article of manufacture of claim 20, wherein the alloy has a reaction rate less than 5% than that of the H13 steel.

26. A casting component for casting aluminum, wherein the casting component is either clad with or is comprised of a metal alloy composition, the metal alloy composition having a reaction level of about 38 atom % or less, wherein the reaction level is defined as the minimum alloy content of the metal alloy composition in the phase diagram between aluminum and the metal alloy composition where the liquidus curve is at or above 1500 K.

27. The casting component of claim 26, wherein the alloy has a reaction rate in molten aluminum of less than or equal to ½ the rate of H13 steel.

28. The casting component of claim 26, wherein a % loss of an alloy rod, based on area loss and diameter loss, formed the metal alloy composition is less than 5% after undergoing a molten aluminum flow rate of 0.2 meters/second.

29. A method of casting aluminum, comprising:

providing molten aluminum into contact with a surface of a casting component, wherein the casting component is either clad with or is comprised of a metal alloy composition, the metal alloy composition having a reaction level of about 38 atom % or less, wherein the reaction level is defined as the minimum alloy content of the metal alloy composition in the phase diagram between aluminum and the metal alloy composition where the liquidus curve is at or above 1500 K; and

casting the molten aluminum.