RMI CORPORATION SECURED PROMISSORY NOTE

Exhibit 10.31

This Secured Promissory Note (this “ Note ”) shall not be sold, offered for sale, pledged, or hypothecated except as permitted herein. Any attempted transfer of this Note in violation of such terms shall be null and void and of no effect. This Note has not been registered under the Securities Act of 1933, as amended (the “ Securities Act ”), and may not be sold unless (i) a registration statement under the Securities Act is in effect therefor or the Borrower has received an opinion of counsel to the effect that registration is not required under the Securities Act in connection with such sale or (ii) it is sold in accordance with Rule 144 promulgated under the Securities Act.

RMI CORPORATION

SECURED PROMISSORY NOTE

FOR VALUE RECEIVED, the undersigned, RMI CORPORATION, a Delaware corporation (the “ Borrower ”), promises to pay to the order of NETLOGIC MICROSYSTEMS, INC., a Delaware corporation (“ Lender ”), or each of its respective assigns and successors, the aggregate principal amount of Fifteen Million and No/100 Dollars ($15,000,000.00), together with accrued and unpaid interest thereon and any other amount owed pursuant to the terms of this Note from the date hereof as provided herein.

1. Payment on the Maturity Date . The Borrower shall pay to Lender on the Maturity Date in full in cash all of the aggregate unpaid principal amount of the indebtedness evidenced by this Note then outstanding, together with all accrued but unpaid interest thereon and any other amount owed hereunder.

2. Interest Rate . Except as expressly provided in Section 3.2(a) hereof, this Note shall bear interest daily at the Applicable Interest Rate on the principal indebtedness evidenced by this Note outstanding from the date of this Note until the Maturity Date or the date upon which the principal indebtedness evidenced by this Note otherwise becomes due and payable (whether by demand or otherwise). Interest shall be calculated on the basis of three hundred sixty (360) day year for the actual number of days elapsed in the period during which it accrues.

3. Default .

3.1 Definition . For purposes of this Note, an Event of Default shall be deemed to have occurred if any one of the following events shall have occurred:

(a) the Borrower fails to pay when due and payable (whether at the Maturity Date or otherwise) the full amount of any principal payment or interest payment on the Note;

(b) an event of default has occurred and is continuing under any other debt instrument of Borrower (including, without limitation, the Pre-Existing Loan Agreements) evidencing debt resulting in the acceleration of the maturity of such indebtedness in an amount in

excess of $500,000; provided, however, that such event of default under this clause (b) caused by the occurrence of a default under such other indebtedness shall be cured or waived for purposes of this Agreement upon Lender receiving written notice from the party asserting such default under such other agreement, if, at the time of such cure or waiver under such other agreement, (a) Lender has not declared an Event of Default hereunder and/or exercised any rights with respect thereto; (b) any such cure or waiver does not result in an Event of Default under any other provision of this Agreement; and (c) in connection with any such cure or waiver under such agreement, the terms of any agreement with such third party are not modified or amended in any manner which could in the good faith judgment of Lender be materially less advantageous to any Loan Party;

(c) other than with respect to any covenant or provision which is the subject of clause (d) below, any Loan Party shall fail or neglect to perform, keep or observe any affirmative covenant or material provision contained herein or in any Loan Document, respectively, on the date that any Loan Party is required to perform, keep or observe such covenant or provision and shall permit the continuance of such failure for 10 days; provided, however, that if the default cannot by its nature be cured within the 10 day period or cannot after diligent attempts by the Borrower be cured within such 10 day period, and such default is likely to be cured within a reasonable time, then Borrower shall have an additional period (which shall not in any case exceed 30 days) to attempt to cure such default, and within such reasonable time period the failure to cure the default shall not be deemed to be an Event of Default);

(d) any Loan Party shall fail or neglect to perform, keep or observe any negative covenant or provision contained herein or in any Loan Document, respectively, on the date that any Loan Party is required to perform, keep or observe such covenant or provision;

(e) (i) any Loan Document or any provision thereof shall cease to be in full force and effect, or shall cease to give Lender Liens, rights, powers and privileges purported to be created thereby in favor of Lender, or (ii) any Liens granted in any of the Collateral in favor of Lender shall be void, voidable, or invalid, or (iii) any involuntary Lien (other than any such Lien which is otherwise permitted pursuant to Section 7 hereof) shall attach to any asset or property of any Loan Party or the Collateral which is not discharged within sixty (60) days after such attachment or within thirty (30) days after notice from Lender, whichever occurs first; or (iv) any Loan Party shall cease operations of its present business without the prior written consent of Lender; or (v) any condition exists or event occurs which has resulted in a Material Adverse Effect;

(f) any Loan Party makes an assignment for the benefit of creditors or admits in writing its inability to pay its debts generally as they become due; or an order, judgment or decree is entered adjudicating any Loan Party bankrupt or insolvent; or any order for relief with respect to any Loan Party is entered under the Federal Bankruptcy Code; or any Loan Party petitions or applies to any tribunal for the appointment of a custodian, trustee, receiver or liquidator of any Loan Party or of any substantial part of the assets of any Loan Party, or commences any proceeding relating to any Loan Party under any bankruptcy, reorganization, arrangement, insolvency, readjustment of debt, dissolution or liquidation law of any jurisdiction;

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or any such petition or application is filed, or any such proceeding is commenced, against any Loan Party and either (a) any Loan Party, as applicable, by any act indicates its approval thereof, consent thereto or acquiescence therein or (b) such petition, application or proceeding is not dismissed within 45 days;

(g) any portion of Borrower’s assets is attached or seized, or a levy is filed against any such assets, or a judgment or judgments is/are entered for the payment of money, individually or in the aggregate, of at least $500,000, or Borrower is enjoined or in any way prevented by court order from conducting any material part of its business;

(h) any material representation or material warranty made by any Loan Party in any Loan Document or in any certificate, document, financial or other written statement furnished at any time by any Loan Party as required pursuant hereto or thereto shall prove to have been misleading in any material respect on the date when made or deemed to have been made;

(i) any event of default by Borrower shall have occurred under Section 12.1(e) (other than a default arising from a failure, despite Borrower’s commercially reasonable best efforts, to obtain the third-party consents referenced in Section 10.1(m) or 8.2 or to meet the condition set forth in Section 8.4(d) of the Agreement) or (f)(i) of that certain Agreement and Plan of Merger Reorganization dated as of the date hereof (the “Merger Agreement”) by and among Lender, Roadster Merger Corporation, Borrower, and the Representative (as defined therein), resulting in the termination of the Merger Agreement by Lender; or

(j) a Change of Control occurs.

3.2 Consequences of Events of Default .

(a) If any Event of Default has occurred, the Applicable Interest Rate shall increase by an increment of two percentage points or, if less, to the maximum amount permitted by law. Any increase of the Applicable Interest Rate resulting from the operation of this Section 3.2(a) shall terminate as of the close of business on the date upon which no Events of Default exist.

(b) If any Event of Default of the type described in Section 3.1(f) has occurred, the aggregate principal amount of this Note (together with all accrued interest thereon and all other amounts due and payable with respect thereto) shall become immediately due and payable without any further action on the part of Lender, and the Borrower shall immediately pay to Lender all amounts due and payable with respect to this Note.

(c) If any Event of Default under Section 3.1 (other than of the type described in Section 3.1(f) ) has occurred, Lender may declare all or any portion of the outstanding principal amount of this Note (together with all accrued interest thereon and all other amounts due and payable with respect thereto) to be immediately due and payable and may demand immediate payment of all or any portion of the outstanding principal amount of this Note, provided, however, that in the case of any Event of Default due to the occurrence of an event of default by Borrower under Section 12.1(e), Borrower may only make the preceding declaration ninety (90) days after such Event of Default and it shall only be effective if not cured by such date.

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(d) If any Event of Default of the type described in Section 3.1(j) has occurred, upon the consummation of the transaction constituting the Change of Control the aggregate principal amount of this Note (together with all accrued interest thereon and all other amounts due and payable with respect thereto) and an additional Five Million and No/100 Dollars ($5,000,000.00) shall be paid to Lender from the proceeds of such Change of Control transaction prior to any creditor, shareholder or other Person (other than the Pre-Existing Lenders) receiving any of such proceeds.

(e) Lender shall also have any other rights which such holder may have been afforded under any contract or agreement with the Borrower at any time and any other rights which such holder may have pursuant to applicable law.

4. Waiver of Presentment and Notice . The Borrower hereby waives diligence, presentment, protest and demand and notice of protest and demand, dishonor and nonpayment of this Note, and expressly agrees that this Note, or any payment hereunder, may be extended from time to time and that Lender may accept security for this Note or release security for this Note, all without in any way affecting the liability of the Borrower hereunder.

5. Representations, Warranties and Agreements . As a material inducement to Lender to provide the indebtedness evidenced by this Note, Borrower hereby, and each Loan Party upon being joined hereto pursuant to Section   6.10, represents and warrants that:

5.1 Each Loan Party is a corporation duly organized, validly existing and in good standing under the laws of its jurisdiction of organization and is qualified to do business as a foreign organization in every jurisdiction where the failure to so qualify could be reasonably expected to have a Material Adverse Effect. Each Loan Party possesses all requisite power and authority and all material licenses, permits and authorizations necessary to own and operate its properties, to carry on its business as now conducted and presently proposed to be conducted and to execute, deliver and perform its obligations under this Note.

5.2 This Note, the Guaranty, the other Loan Documents and any document or other agreement related hereto has been duly authorized, executed, and delivered by the Loan Party thereto and does not conflict with, violate or result in a breach of or require any consent that has not been obtained as of the date hereof under (i) any applicable law, rule or regulation the violation of which could be reasonably expected to have a Material Adverse Effect, (ii) any of the terms of its organizational documents, or (iii) any material agreement or instrument to which any Loan Party is a party or by which any Loan Party is bound.

5.3 This Note constitutes the legal, valid, and binding obligation of each Loan Party, is in full force and effect and enforceable against each Loan Party in accordance with its terms (subject, in each case, to the effect of bankruptcy or other similar laws and to general principles of equity (whether considered in proceedings at law or in equity)).

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5.4 No Default or Event of Default has occurred and is continuing or will occur upon the funding of the Note hereunder.

5.5 All representations and warranties herein and in each other Loan Document shall be true and correct as of the time of execution hereof or thereof and shall survive the execution, delivery and acceptance hereof and thereof by the parties thereto and the closing of the transactions described there in or relating thereto.

6. Covenants . Until the indefeasible payment and satisfaction in full in cash of all obligations of any Loan Party hereunder (including all accrued but unpaid interest) and the termination of this Note, unless any Loan Parties receive the prior written consent of Lender waiving or modifying any of the Loan Party’s covenants hereunder in any specific instance, Borrower hereby, and each Loan Party upon being joined hereto pursuant to Section   6.10 , covenants and agrees as follows:

6.1 Maintenance of Records; Legal Existence . Each Loan Party shall at all times keep accurate and complete books, records and accounts with respect to all of their respective business activities, in accordance with United States generally accepted accounting principles consistently applied, and shall keep such books, records and accounts, and any copies thereof, only at the addresses indicated for such purpose on Exhibit A-1 or such other locations as the Borrower shall notify Lender in accordance with subsection 6.2(a) hereof. Each Loan Party shall maintain its legal existence in good standing in the jurisdiction in which it is organized and in each other jurisdiction where it is required to register or qualify to do business if the failure to do so in such other jurisdiction could reasonably be expected to have a Material Adverse Effect.

6.2 Notices . The Borrower shall:

(a) Locations . Promptly notify Lender of the proposed opening of any new place of business or new location of Collateral (as defined herein) other than such places and locations identified on Exhibit A-2 , the closing of any existing place of business or location of Collateral, any change in the location of any Loan Party’s books, records and accounts (or copies thereof), the opening or closing of any bank account or, if any of the Collateral consists of Goods of a type normally used in more than one state, the use of any such Goods in any state other than a state in which the Borrower has previously advised Lender in writing that such Goods will be used.

(b) Names and Trade Names . Promptly (and in any event within twenty-four hours) notify Lender with respect to the change of its name, and promptly (and in any event within five days) notify Lenders with respect to the use of any trade name, assumed name, fictitious name or division name not previously disclosed to Lender in writing.

(c) Collateral . Promptly (and in any event within 3 days) notify Lender of the existence of any item with respect to which Lender has the option to require to become subject to a separate pledge, assignment and security agreement pursuant to Section 8.4 hereof.

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(d) Material Litigation . A prompt report of any legal actions pending or threatened against Borrower, Loan Party or any of their respective Subsidiaries that could reasonably be expected to result in damages or costs to Borrower, Loan Party or any of their respective Subsidiaries of $500,000 or more, or in which an adverse decision could reasonably be expected to result in a Material Adverse Effect.

All of the foregoing notices and information shall be provided by the Borrower to Lender in writing.

6.3 Compliance with Laws and Maintenance of Permits . Each Loan Party shall maintain all governmental consents, franchises, certificates, licenses, authorizations, approvals and permits, the lack of which could reasonably be expected to have a Material Adverse Effect and each Loan Party shall remain in compliance with all applicable federal, state, local and foreign statutes, orders, regulations, rules and ordinances (including, without limitation, environmental laws and statutes, orders, regulations, rules and ordinances relating to taxes, employer and employee contributions and similar items, securities, ERISA or employee health and safety) the failure with which to comply could reasonably be expected to have a Material Adverse Effect.

6.4 Inspection and Audits . Each Loan Party shall permit Lender to call at its places of business without hindrance or delay to inspect the Collateral and to inspect and audit their books, records, journals, orders, receipts and any correspondence and other data relating to each Loan Party’s business, the Collateral or any transactions between the parties hereto, and shall have the right to make such verification concerning each Loan Party’s business as Lender may consider necessary or advisable under the circumstances.

6.5 Insurance . The Borrower shall keep the Collateral properly insured for the full insurable value thereof against loss or damage by such risks as are customarily insured against by Persons engaged in businesses similar to that of the Borrower, with such companies, in such amounts, with such deductibles, and under policies in such form, as Lender may consider necessary or advisable. Upon Lender’s request, original (or certified) copies of such policies of insurance have been or shall be, within thirty (30) days of the date hereof, delivered to Lender, together with evidence of payment of all premiums therefor, and at Lender’s request, shall contain an endorsement, in form and substance reasonably acceptable to Lender, showing loss under such insurance policies payable to Lender.

6.6 Collateral . Each Loan Party shall keep the Collateral in good condition, repair and order, ordinary wear and tear and damage by casualty excepted. Each Loan Party shall, at the request of Lender, indicate on its records concerning the Collateral a notation, in form reasonably satisfactory to Lender, of the security interest of Lender hereunder.

6.7 Guaranties . Each Loan Party shall not assume, guarantee or endorse, or otherwise become liable in connection with, the obligations of any Person, except (i) by endorsement of instruments for deposit or collection or similar transactions in the ordinary course of business, (ii) swap contracts entered into in the ordinary course of business for bona fide hedging purposes and not for purposes of speculation, (iii) contingent obligations existing on the

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date hereof and disclosed on Schedule 6.7 attached hereto (including extensions and renewals thereof which do not increase the amount or extend the term of such contingent obligations as of the date of such extension or renewal), (iv) contingent obligations incurred in the ordinary course of business with respect to surety and appeal bonds, performance bonds and other similar obligations (exclusive of obligations for the payment of borrowed money), (v) contingent obligations arising under indemnity agreements to title insurers to cause such title insurers to issue title insurance policies required hereunder, or arising under customary indemnification provisions contained in leases, licenses and other agreements entered into the ordinary course of business, (vi) contingent obligations arising with respect to customary indemnification obligations in favor of purchasers in connection with dispositions permitted hereunder, and (vii) obligations of Borrower with respect to indemnification of its officers and directors.

6.8 Indebtedness . Each Loan Party shall not create, incur, assume or become obligated (directly or indirectly), for any loans or other indebtedness for borrowed money other than the indebtedness evidenced hereby and other than such indebtedness outstanding on the date hereof and disclosed on Schedule 6.8 attached hereto (including extensions and renewals thereof which do not increase the amount or extend the term of such indebtedness as of the date of such extension or renewal); provided that the Loan Parties may (i) incur unsecured indebtedness to trade creditors in the ordinary course of business; (ii) incur purchase money indebtedness or capitalized lease obligations in the ordinary course of business in an aggregate principal amount not to exceed $500,000 at any one time outstanding (or such higher amount as may be agreed to by Lender from time to time hereafter in writing); (iii) incur indebtedness not otherwise permitted hereunder in