Corrosion and crack resistant brake disc overlay material

Abstract

A cladding feedstock including iron as the majority element and further including chromium, molybdenum, and titanium, and Fe-based alloys having high corrosion resistance and crack resistance formed therefrom. In particular, Fe-based alloys, such as, for example, a fully ferritic Fe-based alloys that may be used for laser cladding cast iron brake disc to improve wear life, reduce brake dust, and provide corrosion resistance.

Description

[0001] Att’y Docket No. P74197 CORROSION AND CRACK RESISTANT BRAKE DISC OVERLAY MATERIAL CROSS-REFERENCE TO RELATED APPLICATION This International application claims the benefit / priority of U.S. Provisional Application No.63 / 694,454 filed September 13, 2024, the disclosure of which is expressly incorporated by reference herein in its entirety. BACKGROUND 1. FIELD OF THEINVENTIONThis disclosure generally relates to feedstocks and Fe-based alloys having high corrosion resistance and crack resistance, and coatings formed therefrom. In particular, example embodiments of this disclosure relate to Fe-based alloys (such as, for example, a fully ferritic Fe-based alloy) used for laser cladding cast iron brake disc to improve wear life, reduce brake dust, and provide corrosion resistance for, but not limited to, automotive, aerospace, power generation, or general industrial applications. 2. DISCUSSION OF BACKGROUND INFORMATION The automotive industry is increasingly interested in brake discs with improved crack resistance, wear and corrosion. Alternative technologies such as composite brake discs are frequently unattractive for mass production due to high costs. Two factors are driving this market trend. First is the increasing pressure from regulators to reduce fine particulate emissions originating from the wear of brake discs. Second is the decreasing use of friction braking in vehicles capable of regenerative braking resulting the corrosion of cast iron brakes. The visible corrosion (rust) is both an issue of aesthetics and can reduce braking effectiveness. As a result, the alloys and coatings described in this disclosure have high potential for providing the improved brake disc performance the market is interested in. Further, because alloys of this disclosure are iron based, they have a competitive cost compared to more expensive metals and composites. SUMMARY Embodiments are directed to a cladding feedstock that comprises iron (as the majority element) chromium, molybdenum, and titanium. Some embodiments are directed to a {P7419706769132.DOC}7419706766823.DOC} - 1 - Att’y Docket No. P74197 cladding feedstock that may include about 70.4 – 84.0 wt% iron, 14.7 – 27.3 wt% chromium, 0.5 – 1.7 wt% molybdenum, and 0.2 – 1.0 wt% titanium. In some embodiments, this cladding feedstock may optionally include at least one of up to 0.1 wt% carbon, up to 0.5 wt% niobium, up to 1.0 wt% nickel, up to 1.0 wt% manganese, and up to 1.0 wt% silicon. In some embodiments, the cladding feedstock may include about 73.8 – 80.6 wt% iron, 17.9 – 24.2 wt% chromium, 1.0 – 1.5 wt% molybdenum, and 0.4 – 0.8 wt% titanium. Moreover, this cladding feedstock may optionally include at least one of up to 0.1 wt% carbon, up to 0.5 wt% niobium, up to 1.0 wt% nickel, up to 1.0 wt% manganese, and up to 1.0 wt% silicon. Some embodiments are directed to an alloy that includes about 70.4 – 84.0 wt% iron, 14.7 – 27.3 wt% chromium, 0.5 – 1.7 wt% molybdenum, and 0.2 – 1.0 wt% titanium. Moreover, this alloy may optionally include at least one of up to 0.1 wt% carbon, up to 0.5 wt% niobium, up to 1.0 wt% nickel, up to 1.0 wt% manganese, and up to 1.0 wt% silicon. Some embodiments are directed to an alloy that includes about 70.4 – 84.0 wt% iron, 14.7 – 27.3 wt% chromium, 0.8 – 1.7 wt% molybdenum, and 0.2 – 1.0 wt% titanium. Moreover, this alloy may optionally include at least one of up to 0.1 wt% carbon, up to 0.5 wt% niobium, up to 1.0 wt% nickel, up to 1.0 wt% manganese, and up to 1.0 wt% silicon. In accordance with embodiments, the feedstock may have, under thermodynamic conditions, a total ferrite fraction of 50 mol% or greater at all temperatures between the solidus temperature and above 500K. In some embodiments, the feedstock may have, under thermodynamic conditions, a Laves or Sigma phase formation temperature below 1300K. In accordance with embodiments, the feedstock can be formed into a powder through a gas atomization process. In other embodiments, the feedstock can be formed into a wire. In accordance with embodiments, the feedstock can be formed into a coating via laser cladding, ultra-high speed laser cladding, plasma transferred arc welding, or thermal spray. In some embodiments, the coating may have, under thermodynamic conditions, a total ferrite fraction of 50 mol% or greater at all temperatures between the solidus temperature and above 500K. In some embodiments, the coating may have, under thermodynamic conditions, a Laves or Sigma phase formation temperature below 1300K. In some embodiments, the coating has a fully ferritic microstructure, which is free of secondary intermetallic phases (such as Laves or Sigma). In some embodiments, the coating has a hardness of about 450 {P7419706769132.DOC}7419706766823.DOC} - 2 - Att’y Docket No. P74197 HV0.3or lower. Other exemplary embodiments and advantages of the present invention may be ascertained by reviewing the present disclosure and the accompanying drawing. BRIEF DESCRIPTION OF THE DRAWINGS The present invention is further described in the detailed description which follows, in reference to the noted plurality of drawings by way of non-limiting examples of exemplary embodiments of the present invention, in which like reference numerals represent similar parts throughout the several views of the drawings, and wherein: Fig.1 is an illustration of a Schaeffer diagram; Fig.2 is an illustration of an equilibrium phase diagram; Fig.3 is an illustration depicting the “mushy zone”; Fig.4 is an illustration of an x-ray diffraction (XRD) spectrum of Example 1; Fig.5 is an illustration of an XRD spectrum of Example 2; and Fig.6 is an illustration of an XRD spectrum of Example 3. Fig.7 is an illustration of an XRD spectrum of Example 4. Fig.8 is an illustration depicting the coefficient of thermal expansion results for the EHLA coating produced from Example 4. DETAILEDDESCRIPTIONThe particulars shown herein are by way of example and for purposes of illustrative discussion of the embodiments of the present invention only and are presented in the cause of providing what is believed to be the most useful and readily understood description of the principles and conceptual aspects of the present invention. In this regard, no attempt is made to show structural details of the present invention in more detail than is necessary for the fundamental understanding of the present invention, the description taken with the drawings making apparent to those skilled in the art how the several forms of the present invention may be embodied in practice. As used herein, the singular forms “a,” “an,” and “the” include the plural reference unless the context clearly dictates otherwise. For example, reference to “a powder material” would also mean that mixtures of one or more powder materials can be present unless {P7419706769132.DOC}7419706766823.DOC} - 3 - Att’y Docket No. P74197 specifically excluded. As used herein, the indefinite article “a” indicates one as well as more than one and does not necessarily limit its referent noun to the singular. Except where otherwise indicated, all numbers expressing quantities used in the specification and claims are to be understood as being modified in all examples by the term “about.” Accordingly, unless indicated to the contrary, the numerical parameters set forth in the specification and claims are approximations that may vary depending upon the desired properties sought to be obtained by embodiments of the present disclosure. At the very least, and not to be considered as an attempt to limit the application of the doctrine of equivalents to the scope of the claims, each numerical parameter should be construed in light of the number of significant digits and ordinary rounding conventions. Additionally, the recitation of numerical ranges within this specification is considered to be a disclosure of all numerical values and ranges within that range (unless otherwise explicitly indicated). For example, if a range is from about 1 to about 40, it is deemed to include, for example, 1, 7, 23.7, 34, 36.1, 40, or any other value or range within the range. As used herein, the terms “about” and “approximately” indicate that the amount or value in question may be the specific value designated or some other value in its neighborhood. Generally, the terms “about” and “approximately” denoting a certain value is intended to denote a range within ±5% of the value. As one example, the phrase “about 100” denotes a range of 100±5, i.e., the range from 95 to 105. Generally, when the terms “about” and “approximately” are used, it can be expected that similar results or effects according to the disclosure can be obtained within a range of ±5% of the indicated value. The terms “substantially” and “essentially” are used to denote that the following feature, property or parameter (such as, for example, being substantially spherical) is either completely (entirely) realized or satisfied or to a major degree (such as 90%, 95%, or 99% (e.g., in terms of the degree to which a particle approximates the shape of a sphere)) that does not adversely affect the intended result. The term “comprising” as used herein is intended to be non-exclusive and open- ended. Thus, for example a composition comprising alloy A may include other alloys besides A. However, the term “comprising” also covers the more restrictive meanings of “consisting essentially of” and “consisting of”, so that for example “a composition comprising alloy A” may also (essentially) consist of the alloy A. In the present disclosure, unless otherwise noted, all weight percentages (wt%) {P7419706769132.DOC}7419706766823.DOC} - 4 - Att’y Docket No. P74197 pertaining to an element / component of a cladding feedstock / alloy / matrix phase / component of the present are based on the total weight of the cladding feedstock / alloy / matrix phase / component including any unavoidable impurities that may be present. Disclosed herein are embodiments of a feedstock (e.g., a cladding feedstock) and an Fe-based alloy, such as an Fe-based alloy having a ferritic structure, which may be free of secondary intermetallic phases (such as Laves or Sigma). The feedstock / alloys disclosed herein can be manufactured into a powder form using, for example, a gas atomization process, though the particular process is not limiting and other processes can be used as well. The powder may be formed to have a shape and size distribution that is suitable for the selected application and / or deposition process. In some embodiments, the powder may be composed of particles that have an average size (in terms the diameter) in a range of from 135 microns to 165 microns. In some embodiments, the powder may be composed of particles that have a particle size range of 150±15 microns. The powder can then be used in a variety of deposition processes, including laser cladding, ultra-high speed laser cladding, extreme high-speed laser application (EHLA), plasma transferred arc welding (“PTA”), and thermal spray to form a coating. For example, in some embodiments, the feedstock may be configured to be deposited on a cast iron brake disc wear surface via laser cladding or ultra-high speed laser cladding to form a coating on the cast iron brake disc wear surface. In some embodiments, the feedstock may be configured to be deposited on suitable Fe-based substrate (such as, for example, a substrate selected from a mild steel, HSLA steel, nodular iron, white iron, cast iron and / or another Fe- based substrate) via laser cladding, ultra-high speed laser cladding, extreme high-speed laser application (EHLA), plasma transferred arc welding (“PTA”), and thermal spray, to form a coating on the substate. In embodiments, the coating formed on the substrate from the feedstock of the present disclosure may have an average thickness that is suitable for the intended application (e.g., an automotive application, an aerospace application, a power generation, or a general industrial application). In some embodiments, the coating formed on the substrate from the feedstock of the present disclosure may have an average thickness that is in a range of from about 0.1 mm to about 10 mm. In some embodiments, the coating formed on the substrate from the feedstock of the present disclosure may be a solid, fully dense coating. {P7419706769132.DOC}7419706766823.DOC} - 5 - Att’y Docket No. P74197 The term “alloy” as used herein can refer to the chemical composition forming the powder disclosed within, the powder itself, the feedstock itself, a wire, the wire including a powder, the composition of the metal component formed by the heating and / or deposition of the powder, or other methodology. In some embodiments, the feedstock / alloys of the present disclosure may be formed into a wire, such as a solid or cored wire (a sheath containing a powder) for welding or for use as a feedstock for another process may be described by specific chemistries herein. Further, the compositions disclosed below can be from a single wire or a combination of multiple wires. In embodiments, the diameter of the wire may be selected to be suitable for the intended application. In some embodiments, the diameter of the single wire may be in a range of from about 1.2 mm to about 3.2 mm. In some embodiments, the diameter of each of the wires of the combination of multiple wires may be in a range of from about 1.2 mm to about 3.2 mm. In other embodiments, the diameter of the combination of multiple wires may be in a range of from about 1.2 mm to about 3.2 mm. In embodiments of this disclosure, the feedstock (e.g., a cladding feedstock) of the present disclosure can be described by a compositional range (provided in wt%) comprising iron (Fe) as the majority element and further comprising chromium (Cr), molybdenum (Mo), and titanium (Ti). In some embodiments, this feedstock may optionally include carbon (C), niobium (Nb), nickel (Ni), manganese (Mn), and silicon (Si). In a preferred embodiment, the feedstock (e.g., a cladding feedstock) can include about 70.4 – 84.0 wt% Fe, 14.7 – 27.3 wt% Cr, 0.5 – 1.7 wt% Mo, and 0.2 – 1.0 wt% Ti; or can include about 70.4 – 84.0 wt% Fe, 14.7 – 27.3 wt% Cr, 0.8 – 1.7 wt% Mo, and 0.2 – 1.0 wt% Ti. Moreover, in some embodiments, this feedstock may optionally include one or more of C in an amount up to 0.1 wt% C, Nb in an amount up to 0.5 wt% Nb, Ni in an amount up to 1.0 wt% Ni, Mn in an amount up to 1.0 wt% Mn, and Si in an amount up to 1.0 wt% Si. In other embodiments, this feedstock may be free of one or more of C, Nb, Ni, Mn and Si, or free of two or more of C, Nb, Ni, Mn and Si, or free of three, four or all five of C, Nb, Ni, Mn and Si (apart from any unavoidable impurities that may be present). In a further preferred embodiment, the feedstock (e.g., a cladding feedstock) can include about 73.8 – 80.6 wt% Fe, 17.9 – 24.2 wt% Cr, 1.0 – 1.5 wt% Mo, and 0.4 – 0.8 wt% Ti. Moreover, in some embodiments, this feedstock may optionally include one or more of C in an amount up to 0.1 wt% C, Nb in an amount up to 0.5 wt% Nb, Ni in an amount up to 1.0 {P7419706769132.DOC}7419706766823.DOC} - 6 - Att’y Docket No. P74197 wt% Ni, Mn in an amount up to 1.0 wt% Mn, and Si in an amount up to 1.0 wt% Si. In other embodiments, this feedstock may be free of one or more of C, Nb, Ni, Mn and Si, or free of two or more of C, Nb, Ni, Mn and Si, or free of three, four or all five of C, Nb, Ni, Mn and Si (apart from any unavoidable impurities that may be present). In embodiments, the Fe-based alloy of the present disclosure (which may be in the form of a coating) can include about 70.4 – 84.0 wt% Fe, 14.7 – 27.3 wt% Cr, 0.5 – 1.7 wt% Mo, and 0.2 – 1.0 wt% Ti. Moreover, in some embodiments, this Fe-based alloy may optionally include one or more of C in an amount up to 0.1 wt% C, Nb in an amount up to 0.5 wt% Nb, Ni in an amount up to 1.0 wt% Ni, Mn in an amount up to 1.0 wt% Mn, and Si in an amount up to 1.0 wt% Si. In other embodiments, this Fe-based alloy may be free of one or more of C, Nb, Ni, Mn and Si, or free of two or more of C, Nb, Ni, Mn and Si, or free of three, four or all five of C, Nb, Ni, Mn and Si (apart from any unavoidable impurities that may be present). In a preferred embodiment, the Fe-based alloy of the present disclosure (which may be in the form of a coating) can include about 73.8 – 80.6 wt% Fe, 17.9 – 24.2 wt% Cr, 1.0 – 1.5 wt% Mo, and 0.4 – 0.8 wt% Ti. Moreover, in some embodiments, this Fe-based alloy may optionally include one or more of C in an amount up to 0.1 wt% C, Nb in an amount up to 0.5 wt% Nb, Ni in an amount up to 1.0 wt% Ni, Mn in an amount up to 1.0 wt% Mn, and Si in an amount up to 1.0 wt% Si. In other embodiments, this Fe-based alloy may be free of one or more of C, Nb, Ni, Mn and Si, or free of two or more of C, Nb, Ni, Mn and Si, or free of three, four or all five of C, Nb, Ni, Mn and Si (apart from any unavoidable impurities that may be present). In some embodiments, the Fe-based alloy of the present disclosure may comprise an alloy of Example 1, which comprises: Cr: 14.7 – 27.3 wt%, and preferably 17.9 – 24.2 wt%; Mo: 0.5 – 1.7 wt%, and preferably 1.0 – 1.5 wt%; Ti: 0.2 – 1.0 wt%, and preferably 0.4 – 0.8 wt%; and Fe: balance. In some embodiments, the alloy of Example 1 may optionally include up to 0.10 wt% C, and preferably up to 0.05 wt% C. In other embodiments, the alloy of Example 1 may be free of one or more of C, Nb, Ni, Mn and Si, or free of two or more of C, Nb, Ni, Mn and Si, or free of {P7419706769132.DOC}7419706766823.DOC} - 7 - Att’y Docket No. P74197 three, four or all five of C, Nb, Ni, Mn and Si (apart from any unavoidable impurities that may be present). In some embodiments, the feedstock (e.g., a feedstock having a composition that falls within the above-described compositional ranges) may have, under thermodynamic conditions, a total ferrite fraction of 50 mol% or greater at all temperatures between the solidus temperature and above 500K. In preferred embodiments, the feedstock may have, under thermodynamic conditions, a total ferrite fraction of 60 mol% or greater at all temperatures between the solidus temperature and above 500K. In still preferred embodiments, the feedstock may have, under thermodynamic conditions, a total ferrite fraction of 90 mol% or greater at elevated temperatures just below the solidus temperature. In some embodiments, the feedstock (e.g., a feedstock having a composition that falls within the above-described a compositional ranges) may have, under thermodynamic conditions, a total ferrite fraction of 70 vol% or greater at all temperatures between the solidus temperature and above 500K. In preferred embodiments, the feedstock may have, under thermodynamic conditions, a total ferrite fraction of 80 vol% or greater at all temperatures between the solidus temperature and above 500K. In still preferred embodiments, the feedstock may have, under thermodynamic conditions, a total ferrite fraction of 90 vol% or greater at elevated temperatures just below the solidus temperature. In some embodiments, the coating (e.g., a coating formed from the feedstock of the present disclosure via laser cladding, ultra-high speed laser cladding, plasma transferred arc welding, or thermal spray) may be free of free of one or more of C, Nb, Ni, Mn and Si, or free of two or more of C, Nb, Ni, Mn and Si, or free of three, four or all five of C, Nb, Ni, Mn and Si (apart from any unavoidable impurities that may be present). In some embodiments, the coating (e.g., a coating formed from the feedstock of the present disclosure via laser cladding, ultra-high speed laser cladding, plasma transferred arc welding, or thermal spray) may be free of carbides. In some embodiments, the coating (e.g., a coating formed from the feedstock of the present disclosure via laser cladding, ultra-high speed laser cladding, plasma transferred arc welding, or thermal spray) may have, under thermodynamic conditions, a total ferrite fraction of 50 mol% or greater at all temperatures between the solidus temperature and above 500K. In preferred embodiments, the coating may have, under thermodynamic conditions, a total ferrite fraction of 60 mol% or greater at all temperatures between the solidus temperature and above {P7419706769132.DOC}7419706766823.DOC} - 8 - Att’y Docket No. P74197 500K. In still preferred embodiments, the coating may have, under thermodynamic conditions, a total ferrite fraction of 90 mol% or greater at elevated temperatures just below the solidus temperature. In some embodiments, the coating (e.g., a coating formed from the feedstock of the present disclosure via laser cladding, ultra-high speed laser cladding, plasma transferred arc welding, or thermal spray) may have, under thermodynamic conditions, a Laves or Sigma phase formation temperature below 1300K. In preferred embodiments, the coating may have, under thermodynamic conditions, a Laves or Sigma phase formation temperature below 1200K. In still preferred embodiments, the coating may have, under thermodynamic conditions, a Laves or Sigma phase formation temperature below 1100K. In some embodiments, the coating (e.g., a coating formed from the feedstock of the present disclosure via laser cladding, ultra-high speed laser cladding, plasma transferred arc welding, or thermal spray) can comprise of a fully ferritic microstructure, such as, for example, a fully ferritic microstructure that is entirely free of secondary intermetallic phases (such as Laves or Sigma). In some embodiments, the coating (e.g., a coating formed from the feedstock of the present disclosure via laser cladding, ultra-high speed laser cladding, plasma transferred arc welding, or thermal spray) can have a hardness (Vickers hardness) of about 450 HV0.3 or lower. In preferred embodiments, the coating can have a hardness of about 400 HV0.3 or lower. In still preferred embodiments, the coating can have a hardness of about 350 HV0.3or lower. Thermodynamic Criteria The first thermodynamic criteria: The matrix phase of the alloys of the present disclosure may be predicted by using a Schaeffler Diagram. For example, a Schaeffler Diagram can be used to determine if the alloy will be austenitic (A), martensitic (M), ferritic (F), 100% ferritic

[0101] , or a combination thereof, as shown in Fig.1. The criteria calculates the nickel and chromium equivalent values of the alloy which are then plotted on the Schaeffler Diagram to predict the matrix phase. The nickel and chromium equivalent values are calculated using the following equations: Ni Equivalent = Ni wt% + (30 x C wt%) + (0.5 x Mn wt%) Cr Equivalent = Cr wt% + Mo wt% + (0.5 x Si wt%) + (0.5 x Nb wt%) It is important that the nickel and chromium equivalent values be calculated using the {P7419706769132.DOC}7419706766823.DOC} - 9 - Att’y Docket No. P74197 composition of the matrix phase and not the bulk composition of the alloy. In the case of the alloys disclosed herein, the matrix phase is ferrite (BCC_A2). Many Fe-based alloys form secondary phase during solidification and cooling. Secondary phases may include carbides, borides and / or intermetallics. The formation of these secondary phases consumes some of the alloying elements from the bulk composition. As a result, the composition of the matrix phase can differ from that of the bulk alloy composition. Calculating the nickel and chromium equivalent values using the matrix composition, shown in Fig.2, ensures an accurate prediction of the matrix phase. The nickel and chromium equivalent criteria are calculated using the composition of ferrite (BCC_A2) taken from the equilibrium phase diagram at 1300K

[0201] . For the alloys disclosed, ferrite is the desired matrix phase as predicted by the Schaeffler Diagram

[0101] (see Fig.1). In some embodiments, the alloy matrix chemistry at 1300K falls within the ferrite region or martensite plus ferrite region on the Schaeffler Diagram. In preferred embodiments, the alloy matrix chemistry at 1300K falls only within the ferrite region on the Schaeffler Diagram. Second thermodynamic criteria: The mushy zone. The mushy zone may be used to predict the susceptibility of an alloy to hot cracking or solidification cracking. The mushy zone, shown in Fig.3, is defined as the temperature difference between the liquids and solidus temperatures

[0301] . The liquidus temperature is defined as the temperature at which the first solid phase begins to form

[0302] . The solidus temperature is defined as the temperature at which the alloy has completely solidified

[0303] . Lower mushy zone values indicate alloys with lower tendencies for hot cracking or solidifications cracking. Additionally, a low mushy zone is desirable to promote fast solidification of the alloy to reduce compositional inhomogeneities. In some embodiments, the mushy zone (i.e., the difference between the liquidus and solidus temperatures) of the alloys of the present disclosure is 70K or less. In preferred embodiments, the mushy zone of the alloys of the present disclosure is 60K or less. In still preferred embodiments, the mushy zone of the alloys of the present disclosure is 50K or less. While there is no preferred lower limit, as a practical matter, the mushy zone will generally be greater than or equal to 5K or 10K. Third thermodynamic criteria: the Cr content in the matrix phase, which may be used to predict the alloy’s corrosion resistance. The chromium content in the matrix phase {P7419706769132.DOC}7419706766823.DOC} - 10 - Att’y Docket No. P74197 (BCC_A2) is calculated at 1300K

[0201] . Generally, a higher Cr content in the matrix will provide better corrosion resistance. In some embodiments, the Cr content in the matrix at 1300K is greater than 15 wt%. In preferred embodiments, the Cr content in the matrix at 1300K is greater than 17 wt%. In still preferred embodiments, the Cr content in the matrix at 1300K is greater than 19 wt%. Additionally, corrosion resistance can be predicted with a pitting resistance equivalent number (PREN). This number is calculated as PREN = Cr + 3.3 * (Mo + 0.5 * W) + 16 * N, where the elemental values are in weight percent. The PREN is calculated using the matrix (BCC_A2) composition at 1300K

[0201] . Higher PREN values equate to improve corrosion performance. In some embodiments, the PREN at 1300K is greater than 17. In preferred embodiments the PREN at 1300K is greater than 19. In still preferred embodiments the PREN at 1300K is greater than 21. Fourth thermodynamic criteria: the formation temperature of undesirable intermetallic phases

[0202] , which may be used to predict the alloy’s susceptibility to stress cracking. This criteria looks at the formation temperature of undesirable intermetallic phases

[0202] , which, if present in the alloy’s microstructure, cause embrittlement and increase the alloy’s susceptibility to stress cracking. Lower intermetallic phase formation temperatures suggest the phase will not form in the alloy’s microstructure. Some alloys of the present disclosure may be predicted to form the intermetallic phases Laves and Sigma. In some embodiments, the formation temperature of Laves and Sigma is below 1300K. In preferred embodiments, the formation temperature of Laves and Sigma is below 1200K. In still preferred embodiments, the formation temperature of Laves and Sigma is below 1100K. Fifth thermodynamic criteria: alloy’s liquidus temperature, which may be used to predict the alloy’s manufacturability into an inert gas atomized powder. High liquidus temperatures can reduce powder yield during atomization or render the alloy impossible to produce as a gas atomized powder. In some embodiments, the liquidus temperature of the alloy is less than 2000K. In preferred embodiments, the liquidus temperature is less than 1900K. In still preferred embodiments, the liquidus temperature is less than 1800K. Microstructure Criteria {P7419706769132.DOC}7419706766823.DOC} - 11 - Att’y Docket No. P74197 In some embodiments, the alloys of this disclosure may be fully described by their microstructural features. The microstructure of the embodiments provides advantageous material properties. Some embodiments disclosed herein may be designed to form an alloy which is fully ferritic. There are two advantages to forming a fully ferritic alloy. The first is related to hardness. A fully ferritic microstructure will have a relatively lower hardness compared to an alloy that is partially or fully martensitic. Alloys with higher hardnesses generally will be more crack susceptible during the laser cladding process. In addition, as a brake disc coating, the alloy will undergo continuous thermal cycling during each braking event, further stressing the coating. A soft, ferritic alloy will be more resistant to cracking during the thermal cycling. The second advantage is related to the materials coefficient of thermal expansion (CTE). During thermal cycling the CTE of the coating should match as closely as possible to the substate, in this case cast iron. This will reduce the buildup of internal stresses between the coating and substrate during thermal cycling and help to prevent crack formation and delamination of the coating. The CTE of most cast irons will fall within the range of 10.5 – 14.0 (10-6 / K). The CTE of iron-based ferritic alloys will match closely to cast iron and generally fall within the range of 10.0 – 12.0 (10-6 / K). In some embodiments, the matrix phase is greater than 50 mol% ferrite. In preferred embodiments, the matrix phase is greater than 60 mol% ferrite. In still preferred embodiments, the matrix phase is greater than 90 mol% ferrite. In some embodiments, the matrix phase is greater than 70 vol% ferrite. In preferred embodiments, the matrix phase is greater than 80 vol% ferrite. In still preferred embodiments, the matrix phase is greater than 90 vol% ferrite. In some embodiments, the alloy microstructure contains less than 10 vol% Laves and Sigma phases. In preferred embodiments, the alloy microstructure contains less than 5 vol% Laves and Sigma phases. In still preferred embodiments, the alloys microstructure contains less than 1 vol% Laves and Sigma phases. Performance Criteria In some embodiments, the coating (e.g., a coating formed from the feedstock of the present disclosure via laser cladding, ultra-high speed laser cladding, plasma transferred arc welding, or thermal spray) can have a hardness of about 450 HV0.3 or lower. In preferred embodiments, the coating (e.g., a coating formed from the feedstock of the present disclosure {P7419706769132.DOC}7419706766823.DOC} - 12 - Att’y Docket No. P74197 via laser cladding, ultra-high speed laser cladding, plasma transferred arc welding, or thermal spray) can have a hardness of about 400 HV0.3 or lower. In still preferred embodiments, the coating (e.g., a coating formed from the feedstock of the present disclosure via laser cladding, ultra-high speed laser cladding, plasma transferred arc welding, or thermal spray) can have a hardness of about 350 HV0.3 or lower. The embodiments disclosed are directed to alloys with increased crack resistance. In some embodiments, the crack density (which is the summation of all crack lengths divided by the total area evaluated) contained in the coating is less than 1.5 mm / mm2, preferably less than 1.0 mm / mm2, and more preferably less than 0.5 mm / mm2. In preferred embodiments, the alloy can be applied as a coating free of cracks. In some embodiments, the coating (e.g., a coating formed from the feedstock of the present disclosure via laser cladding, ultra-high speed laser cladding, plasma transferred arc welding, or thermal spray) can have a thermal conductivity of about 14 – 27 (W / mK) at 25°C. In preferred embodiments, the coating (e.g., a coating formed from the feedstock of the present disclosure via laser cladding, ultra-high speed laser cladding, plasma transferred arc welding, or thermal spray) can have a thermal conductivity of about 17 – 25 (W / mK) at 25°C. In still preferred embodiments, the coating (e.g., a coating formed from the feedstock of the present disclosure via laser cladding, ultra-high speed laser cladding, plasma transferred arc welding, or thermal spray) can have a thermal conductivity of about 19 – 22 (W / mK) at 25°C. In some embodiments, the coating (e.g., a coating formed from the feedstock of the present disclosure via laser cladding, ultra-high speed laser cladding, plasma transferred arc welding, or thermal spray) can have a coefficient of thermal expansion (CTE) of about 9 – 17 (x10-6 / K) from 25 - 1000°C. In preferred embodiments, the coating (e.g., a coating formed from the feedstock of the present disclosure via laser cladding, ultra-high speed laser cladding, plasma transferred arc welding, or thermal spray) can have a CTE of about 11 - 15 (x10-6 / K) between 25 - 1000°C. In still preferred embodiments, the coating (e.g., a coating formed from the feedstock of the present disclosure via laser cladding, ultra-high speed laser cladding, plasma transferred arc welding, or thermal spray) can have a CTE of about 12 - 14 (x10-6 / K) between 25 - 1000°C. In some embodiments, the coating (e.g., a coating formed from the feedstock of the present disclosure via laser cladding, ultra-high speed laser cladding, plasma transferred arc {P7419706769132.DOC}7419706766823.DOC} - 13 - Att’y Docket No. P74197 welding, or thermal spray) can have a yield strength of 314 – 583 (MPa) at 25°C. In preferred embodiments, the coating (e.g., a coating formed from the feedstock of the present disclosure via laser cladding, ultra-high speed laser cladding, plasma transferred arc welding, or thermal spray) can have a yield strength of 381 – 515 (MPa) at 25°C. In still preferred embodiments, the coating (e.g., a coating formed from the feedstock of the present disclosure via laser cladding, ultra-high speed laser cladding, plasma transferred arc welding, or thermal spray) can have a yield strength of 426 – 471 (MPa) at 25°C. In some embodiments, the coating (e.g., a coating formed from the feedstock of the present disclosure via laser cladding, ultra-high speed laser cladding, plasma transferred arc welding, or thermal spray) can have a tensile strength of 372 – 690 (MPa) at 25°C. In preferred embodiments, the coating (e.g., a coating formed from the feedstock of the present disclosure via laser cladding, ultra-high speed laser cladding, plasma transferred arc welding, or thermal spray) can have a tensile strength of 451 – 610 (MPa) at 25°C. In still preferred embodiments, the coating (e.g., a coating formed from the feedstock of the present disclosure via laser cladding, ultra-high speed laser cladding, plasma transferred arc welding, or thermal spray) can have a tensile strength of 504 – 557 (MPa) at 25°C. In some embodiments, the coating (e.g., a coating formed from the feedstock of the present disclosure via laser cladding, ultra-high speed laser cladding, plasma transferred arc welding, or thermal spray) can have an elastic modulus of 124 – 230 (GPa) at 25°C. In preferred embodiments, the coating (e.g., a coating formed from the feedstock of the present disclosure via laser cladding, ultra-high speed laser cladding, plasma transferred arc welding, or thermal spray) can have an elastic modulus of 150 – 203 (GPa) at 25°C. In still preferred embodiments, the coating (e.g., a coating formed from the feedstock of the present disclosure via laser cladding, ultra-high speed laser cladding, plasma transferred arc welding, or thermal spray) can have an elastic modulus of 168 – 186 (GPa) at 25°C. In some embodiments, the coating (e.g., a coating formed from the feedstock of the present disclosure via laser cladding, ultra-high speed laser cladding, plasma transferred arc welding, or thermal spray) can have a % elongation in 4D of 8 – 15 % at 25°C. In preferred embodiments, the coating (e.g., a coating formed from the feedstock of the present disclosure via laser cladding, ultra-high speed laser cladding, plasma transferred arc welding, or thermal spray) can have a % elongation in 4D of 10 – 14% at 25°C. In still preferred embodiments, the coating (e.g., a coating formed from the feedstock of the present disclosure via laser cladding, ultra-high speed laser cladding, plasma transferred arc welding, or thermal spray) {P7419706769132.DOC}7419706766823.DOC} - 14 - Att’y Docket No. P74197 can have % elongation in 4D of 11 – 13 % at 25°C. The compositions of US 2017 / 0080531A1 are outside the scope of the embodiments of the present disclosure (e.g., the embodiments of the present disclosure are distinguishable from the compositions of US 2017 / 0080531A1 in that the embodiments of the present disclosure have lower tensile strength, lower yield strength, higher ductility, and / or improved crack resistance compared to the compositions disclosed in US 2017 / 0080531A1). For example, a representative exemplary composition of US 2017 / 0080531A1 exhibits a hardness of greater than 350 HV0.3, a tensile strength of 1062 MPa at 25°C, a yield strength of 881 MPa at 25°C, and an elongation in 4D of 5% at 25°C. The embodiments of the present disclosure are intended to have a lower tensile and yield strength to allow for higher ductility (greater than 5% elongation in 4D). The increased ductility of the embodiments in combination with a ferritic microstructure, and a CTE more similarly matched to cast iron, allow for improved crack resistance over the compositions disclosed in US 2017 / 0080531A1. The present invention is further illustrated by the following non-limiting examples where all parts, percentages, proportions, and ratios are by weight, all temperatures are in °C., and all pressures are atmospheric unless otherwise indicated: EXAMPLES Various example alloys from the teachings of this disclosure were prepared as discussed below. Example 1: Alloy P191-X3 (X3) cast as an ingot. Table I (below) shows the composition measured by energy dispersive spectroscopy (EDS) in wt% and hardness of the X3 ingot. Table I: X3 Ingot EDS Composition and Hardness Alloy Cr Mo Fe Si Hardness (HV0.3) Fig.4 shows an x-ray diffraction (XRD) spectrum of Example 1. The XRD results show the alloy is fully ferritic, no other peaks are present in the XRD spectrum to suggest the existence of secondary phases

[0401] . This is also important as the embodiments are designed {P7419706769132.DOC}7419706766823.DOC} - 15 - Att’y Docket No. P74197 to avoid the formation of embrittling intermetallic phases (Laves and Sigma), forming a 100% ferritic microstructure. Example 2: Alloy X3 was produced into a powder by inert gas atomization. Table II shows the composition of the gas atomized X3 powder in wt%. Table II: Composition of Gas Atomized X3 Powder Alloy C Si Ti g. s ows e specrum o xamp e . e resu s s ow e a oy powder is fully ferritic, no other peaks are present in the XRD spectrum to suggest the existence of secondary phases

[0501] . This is also important as the embodiments are designed to avoid the formation of embrittling intermetallic phases (Laves and Sigma), forming a 100% ferritic microstructure. Example 3: Alloy X3 was PTA welded using the gas atomized powder of Example 2. The PTA parameters and hardness of the weld overlay are shown in Table III. Table III: X3 PTA Parameters and Overlay Hardness Voltage Amperage Powder Travel Oscillation Overlay Overlay Overlay ss ) Fig.6 shows an XRD spectrum of Example 3. Like the previous two Examples, the XRD results show the alloy as a weld overlay is fully ferritic, no other peaks are present in the XRD spectrum to suggest the existence of secondary phases

[0601] . Example 4: Alloy X3 was ultra-high speed laser clad (EHLA) using the gas atomized powder of Example 2. The EHLA parameters and hardness of the overlay are shown in Table IV. {P7419706769132.DOC}7419706766823.DOC} - 16 - Att’y Docket No. P74197 Table IV: X3 EHLA Parameters and Overlay Hardness Laser Laser Spot Process Powder Overlap Overlay Overlay Power Size (mm) Speed Feed Rate Thickness Hardness Fig.7 shows an XRD spectrum of Example 4. Like the previous three Examples, the XRD results show the alloy as an EHLA overlay is fully ferritic, no other peaks are present in the XRD spectrum to suggest the existence of secondary phases

[0701] . Table V shows the thermal conductivity results for the EHLA coating produced from Example 4. Table V: X3 EHLA Overlay Thermal Conductivity Results Temperature Specific Heat °3 2) Fig.8 shows the coefficient of thermal expansion results for the EHLA coating produced from Example 4. Table VI shows the tensile testing results at 25°C for the EHLA coating produced from Example 4. {P7419706769132.DOC}7419706766823.DOC} - 17 - Att’y Docket No. P74197 Table VI: X3 EHLA Overlay Tensile Testing Results Sample Tensile Strength Yield Strength Elongation in Modulus (GPa) N (MPa) 0.2% Offset 4D It is noted that the foregoing examples have been provided merely for the purpose of explanation and are in no way to be construed as limiting of the present invention. While the present invention has been described with reference to an exemplary embodiment, it is understood that the words which have been used herein are words of description and illustration, rather than words of limitation. Changes may be made, within the purview of the appended claims, as presently stated and as amended, without departing from the scope and spirit of the present invention in its aspects. Although the present invention has been described herein with reference to particular means, materials and embodiments, the present invention is not intended to be limited to the particulars disclosed herein; rather, the present invention extends to all functionally equivalent structures, methods and uses, such as are within the scope of the appended claims. {P7419706769132.DOC}7419706766823.DOC} - 18 -

Claims

Att’y Docket No. P74197 CLAIMS What is Claimed:

1. A cladding feedstock comprising, based on the weight of the cladding feedstock: 70.4 – 84.0 wt% iron, 14.7 – 27.3 wt% chromium, 0.5 – 1.7 wt% molybdenum, and 0.2 – 1.0 wt% titanium.

2. The cladding feedstock according to claim 1, further comprising at least one member selected from the group consisting of: (a) carbon in an amount up to 0.1 wt%, (b) niobium in an amount up to 0.5 wt%, (c) nickel in an amount up to 1.0 wt%, (d) manganese in an amount up to 1.0 wt%, and (e) silicon in an amount up to 1.0 wt.%.

3. A cladding feedstock comprising, based on the weight of the cladding feedstock: 73.8 – 80.6 wt% iron, 17.9 – 24.2 wt% chromium, 1.0 – 1.5 wt% molybdenum, and 0.4 – 0.8 wt% titanium.

4. The cladding feedstock according to claim 3, further comprising at least one member selected from the group consisting of: (a) carbon, when included, present in an amount up to 0.1 wt%, (b) niobium, when included, present in an amount up to 0.5 wt%, (c) nickel, when included, is present in an amount up to 1.0 wt%, (d) manganese, when included, is present in an amount up to 1.0 wt%, and {P7419706769132.DOC}7419706766823.DOC} - 19 -Att’y Docket No. P74197 (e) silicon, when included, is present in an amount up to 1.0 wt.%.

5. The cladding feedstock of any of the proceeding claims, wherein the feedstock has, under thermodynamic equilibrium conditions, a total ferrite phase fraction of about 50 mol% or higher at all temperatures below the solidus and above 500 K.

6. The cladding feedstock of any of the proceeding claims, wherein the feedstock has, under thermodynamic conditions, a Laves or Sigma phase formation temperature below 1300K.

7. The cladding feedstock of any of the proceeding claims, wherein a total ferrite phase fraction is about 60 mol% or higher at all temperatures below the solidus and above 500 K.

8. The cladding feedstock of any of the proceeding claims, wherein the feedstock is in the form of a powder, the powder being formed via a gas atomization process.

9. The cladding feedstock of any of the proceeding claims, wherein the feedstock is in the form of a wire.

10. A coating formed from the feedstock of any of the proceeding claims.

11. The coating of claim 10, wherein the coating is formed via laser cladding, ultra- high speed laser cladding, plasma transferred arc welding, or thermal spray.

12. The coating of claim 10 or claim 11, wherein the coating has, under thermodynamic conditions, a total ferrite fraction of 50 mol% or greater at all temperatures between the solidus temperature and above 500K.

13. The coating of any one of claims 10-12, wherein the coating has, under thermodynamic conditions, a Laves or Sigma phase formation temperature below 1300K.

14. The coating of any one of claims 10-13, wherein the coating has a fully ferritic microstructure that is free of secondary intermetallic phases.

15. The coating of any one of claims 10-14, wherein the coating has a hardness of about 450 HV0.3or lower.

16. The coating of any one of claims 10-15, wherein the coating is free of one or more of C, Nb, Ni, Mn and Si.

17. The coating of any one of claims 10-15, wherein the coating is free of carbides. {P7419706769132.DOC}7419706766823.DOC} - 20 -

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